Update - I have two hot replication slaves of this db, both have the problem. I took one out of recovery and ran REINDEX table session_session and it fixed the errors about this row. Now Im going to run vacuum and see if there are other tables that complain, but Im guessing if so I will need to see if there is a way to force vacuum to continue on error, worst case I might have to script a table by table vacuum script I guess.. If anyone has a better suggestion for determining the extent of the damage Id appreciate it.