iptables why rejects this output?

[BAGI Ákos <abagi@compuflex.hu>]

Hi List!

This is in the log:
Oct  4 22:28:37 atilla kernel: [15888959.848503] IPTABLES OUTPUT reject 
IN= OUT=eth0 SRC=aa.bb.bb.dd DST=ee.ff.gg.hh LEN=40 TOS=0x00 PREC=0x00 
TTL=64 ID=4940 DF PROTO=TCP SPT=443 DPT=53983 WINDOW=237 RES=0x00 ACK 
FIN URGP=0
I'm interested the ending:
WINDOW=237 RES=0x00 ACK FIN URGP=0

The client is logged in and communicates fine with the apache server 
with ssl.
However sometimes come such log entries.

What does this entry mean?
What is not enabled if all responses are enabled (ESTABLISHED, RELATED)

How can I enable it with iptables? (I have lot of iptables rules).
Is it ok, to enable  it?

Thx:
A