Sounds like you might have a "trigger_file" set in your recovery.conf. Do you? That or someone is issuing a pg_ctl promote command.
I'm using PostgreSQL 9.2.4 on x86_64-unknown-linux-gnu, compiled by gcc (GCC) 4.1.2 20070115 (SUSE Linux), 64-bit.
I set up streaming replication for a read/write primary and a read/only standby. The replication works fine for a while, and then out of the blue BOTH machines become read/write, but with no replication from the original primary to the newly read/write standby.
The only log entry that seems relevant is as follows: FATAL,57P01,"terminating walreceiver process due to administrator command",,,,,,,,"ProcessWalRcvInterrupts, walreceiver.c:150",""
Any help/guidance would be appreciated. Thanks in advance.