Unexplained greylist non-delivery

I have now found two cases where it appears that the greylister should 
have delivered a message and did not. As an example here are two 
excerpts from the maillog:

Oct  2 11:59:45 mx01 sendmail[20134]: k92HxdCf020134: 
from=<Michelle.Faurot@Newsweek.com>, size=26890, class=0, nrcpts=1, 
msgid=<OFEBFF9E38.277463EB-ON852571FB.006044CD-852571FB.0062D713@newsweekmag.com>, 
proto=ESMTP, daemon=MTA, relay=nw-smtp.newsweekmag.com [66.151.126.34]
Oct  2 11:59:45 mx01 sendmail[20134]: k92HxdCf020134: Milter change 
(add): header: X-DCC-Misty-Metrics: mx01.mric.net 1170; Body=1 Fuz1=2 Fuz2=2
Oct  2 11:59:45 mx01 sendmail[20134]: k92HxdCf020134: Milter: data, 
reject=452 4.2.1 mail k92HxdCf020134 from 66.151.126.34 temporary 
greylist embargoed
Oct  2 11:59:45 mx01 sendmail[20134]: k92HxdCf020134: 
to=<lfaurot@mric.net>, delay=00:00:00, pri=56890, stat=mail 
k92HxdCf020134 from 66.151.126.34 temporary greylist embargoed

Oct  2 12:12:28 mx01 sendmail[21540]: k92ICMWS021540: 
from=<Michelle.Faurot@Newsweek.com>, size=26890, class=0, nrcpts=1, 
msgid=<OFEBFF9E38.277463EB-ON852571FB.006044CD-852571FB.0062D713@newsweekmag.com>, 
proto=ESMTP, daemon=MTA, relay=nw-smtp.newsweekmag.com [66.151.126.34]
Oct  2 12:12:28 mx01 sendmail[21540]: k92ICMWS021540: Milter change 
(add): header: X-DCC--Metrics: mx01.mric.net 1114; Body=1 Fuz1=2 Fuz2=2
Oct  2 12:12:28 mx01 sendmail[21540]: k92ICMWS021540: Milter: data, 
reject=452 4.2.1 mail k92ICMWS021540 from 66.151.126.34 temporary 
greylist embargoed
Oct  2 12:12:28 mx01 sendmail[21540]: k92ICMWS021540: 
to=<lfaurot@mric.net>, delay=00:00:01, pri=56890, stat=mail 
k92ICMWS021540 from 66.151.126.34 temporary greylist embargoed

Notice that over 12 minutes have elapsed and it looks like all 
requirements for delivery have been met. However, when I go to the DCC 
logs I  find:

dccm  global

X-DCC-Misty-Metrics: mx01.mric.net 1170; Body=1 Fuz1=2 Fuz2=2
                            reported: 1               checksum  server
                       IP: 181f8c37 8b611448 828bf81e c88325b4
                 env_From: 326f7cf1 94ef6f51 1630d45a 535bad92
                     From: 520936c2 dd84523f e713301c 12c31373
          substitute helo: c0f347e2 5ec4abb4 341523ba e4145a98
               Message-ID: 04d35f9e f090aab0 e0c6757a c833ebc1
                     Body: 8a9583f0 225f2048 3a9580a3 5fe44404       0
                     Fuz1: a5ed1444 3b3afa18 0975e109 be098af4       1
                     Fuz2: 87bb879c 7eb16b59 6b8ace82 ef4e4ca9       1
     substitute mail_host: d1d4c51d f13203e2 af3ede62 88dccfbc

       greylist recipient
         lfaurot@mric.net: beeeffe9 8e39eccf 22af1b4f d99e4936
                           e3eb0916 aa023c6a 44e966a0 ede1562c Embargo #1

rejection message: 452 4.2.1 mail k92HxdCf020134 from 66.151.126.34 
temporary greylist embargoed
result: temporary greylist embargo

dccm  global

X-DCC--Metrics: mx01.mric.net 1114; Body=1 Fuz1=2 Fuz2=2
                            reported: 1               checksum  server
                       IP: 181f8c37 8b611448 828bf81e c88325b4
                 env_From: 326f7cf1 94ef6f51 1630d45a 535bad92
                     From: 520936c2 dd84523f e713301c 12c31373
          substitute helo: c0f347e2 5ec4abb4 341523ba e4145a98
               Message-ID: 04d35f9e f090aab0 e0c6757a c833ebc1
                     Body: 8d674e22 40ea6410 897585da 498c21ad       0
                     Fuz1: a5ed1444 3b3afa18 0975e109 be098af4       1
                     Fuz2: 87bb879c 7eb16b59 6b8ace82 ef4e4ca9       1
     substitute mail_host: d1d4c51d f13203e2 af3ede62 88dccfbc

       greylist recipient
         lfaurot@mric.net: cfe9fd0d 96af0e1d ef25bf6b cba8bd52
                           e3eb0916 aa023c6a 44e966a0 ede1562c Embargo #1

rejection message: 452 4.2.1 mail k92ICMWS021540 from 66.151.126.34 
temporary greylist embargoed
result: temporary greylist embargo

The checksums for the same recipient lfaurot@mric.net are different. I 
don't understand how this can occur and I assume this is the root cause 
for the non-delivery. Is this a possible DCC issue or can the sending 
server really be doing something to the recipient address such that the 
message can find its way to my email server but yet not have a proper 
checksum from delivery attempt to next delivery attempt?

-- 
Paul (ganci@nurdog.com)