Could it be that baby moved? My baby was posterior @ 32 weeks. About 3 Fridays ago i had really bad back pain. Was on the lounge room floor in all four possi rocking to and fro to lighten the pain in my back (DH thought i was in labour, but no, just comfy possi for me). Anyway, when i went to clinic on Monday, bubs had moved.....no longer posterior......just a thought it might have happened to you too...????