Many not-new hits from port 80 when surfing their site

Several times now, I have seen a lot of entries in syslog which seem to be associated with browsing a particular site, but for some reason get dropped as "not-new". For example, when browsing the thinkgeek site, messages like this appear maybe 50 times, with slightly different destination port numbers:

Dec 29 06:39:45 IPTABLES NOT-NEW-IN: SRC=66.35.250.160 \
     LEN=48 TTL=45 ID=0 DF PROTO=TCP SPT=80 DPT=4785 \
     WINDOW=5840 RES=0x00 ACK SYN URGP=0 

Always from port 80 on the remote machine, but the source address is a site I'm accessing. What's causing this, should I be concerned, and can/should I fix it? The rules that produce this is (in iptables-restore format):

-A INPUT -p tcp -m tcp --tcp-flags ! SYN,RST,ACK SYN \
     -m state --state NEW -j LOG --log-prefix "IPTABLES NOT-NEW-IN: "
-A INPUT -p tcp -m tcp --tcp-flags ! SYN,RST,ACK SYN \
     -m state --state NEW -j DROP

If I already have a session open with the remote site, why are these not being associated? Any help will be appreciated.

Thanks,

Andy Johnson

Please see the archive. This has been asked and answered about 3 times in the last month. Short answer, its a time-out issue during session tear down and not something to worry about. ;-)

C