Postgresql - Minor version upgrade 9.3.5 to 9.3.6 on Ubuntu
I'm guessing your log on server A is being shared by the two databases (master of A and the slave of B).

It looks like you have set ssl = on in your master's postgresql.conf file and have set ssl = off in your slave(B). You should either set ssl to on on all servers or none.

PostgreSQL doesn't usually have a problem replicating across minor versions