floating keep state

[Vadym Chepkov]

I created a lab configuration with the minimum settings

dns server has ip 10.10.10.1
client has ip 10.10.11.254
between them is 6.3-RELEASE-p1 with 10.10.10.6 and 10.10.11.1 interfaces

here is /etc/pf.conf

set block-policy return
set state-policy floating
pass in log quick proto udp from any to 10.10.10.1 port domain keep state
block in log from any to 10.10.11.254

Now I make nslookup on the client, here is the output of tcpdump -n -l
-e -i pflog0

22:58:14.296303 rule 0/0(match): pass in on xl1: 10.10.11.254.32772 >
10.10.10.1.53:  45616+[|domain]
22:58:14.296965 rule 1/0(match): block in on xl0: 10.10.10.1.53 >
10.10.11.254.32772:  45616*-[|domain]

State is
#pfctl -ss
self udp 10.10.10.1:53 <- 10.10.11.254:32772       NO_TRAFFIC:SINGLE

My question is, why the reply packet was blocked?