Understanding pf with FTP on IPv6

[Philip Dodd <philip.dodd%free.fr@localhost>]

Hi,

I am running a dual-stack host that I'm currently seeing a strange 
issue (or at least an issue I don't understand :) ) with outgoing 
(client) FTP connections over IPv6.

Basically my pf.conf contains a "block in all" at the start and a bunch 
of rules that allow some stuff to connect on regular ports inbound.

FTP client (outbound) from this host works fine over IPv4 but will fail 
over IPv6 unless I comment out this line.

Is this difference in behaviour expected?

Any thoughts much appreciated.

Best regards,

Phil