Ah, I think I have a better understanding of what is really happening here.
The only IP addresses that are showing up are ones that are for a Microsoft Load Balanced IP with two members. I guessing what is getting blocked are the packets that are viewed as out of order by the non-active based on the fact that the primary firewall has already gotten past the part of the connection setup that a given packet type would be expected.
So sorry for the false-alarm. I just noticed when I went back through the logs that it was only happening on the LB IPs.
The more I'm exposed to this implementation of load balancing the less I like it–unfortunately, we are committed to this at least for the near future.