ident authentication problems postgresql 9.2

I have just done an update on my Debian servers running postgresql 9.2
(Postgres is from 9.2.4-2.pgdg70+1 from apt.postgresql.org) and suddenly
can't login to postgresql as postgres with the normal peer/ident
authentication over a local Unix socket.

I've worked around it (I'm using md5 for the time being) but I wonder if
anyone else has experienced this problem which is affecting all 3 of my
9.2 servers.

I can't find anything in the recent Debian security updates that could
have broken this (i.e. recent stuff at http://www.debian.org/security/)

By the way there is a key expired error on http://apt.postgresql.org.

Regards
Rory