Connections refused during backups

[Glen Eustace <geustace@xxxxxxxxxxxxxx>]

After an upgrade from 8.0.8 to 8.1.8, I am getting a number of our 
scripts failing with 'connection refused' at around 4:00am, which seems 
to be when the nightly database backup occurs.

I am using "/usr/bin/pg_dump -Fc -b -c -C" to do the deed.

Has there been a change in behavior, i.e. is the whole databases being 
exclusively locked or something that would prevent a connection.