The issue with a PFO is that you may not have off gassed everything from the first dive and there were a few saw teeth in it that may have created some silent bubbles, at relatively shallow depths where pressure change is greater.
Many of the so called unearned DCS hits in the recreational community inside recommended NDL's are attributable to PFO's, where theoretically only very low levels of bubbling should/will have occurred.
Another explanation could be that you simply had a migraine under water, which I think Mark has also had, resulting in blown off deco. Its the aura then which would suggest a possible PFO even if you didn't get bent.
The worry for me even now, is that given that I dived from the age of 5 on and off to the age 28 with a PFO, there may be lesions and latent damage that I won't know about until they manifest at some point sooner or later and usually they are on the important grey squashy bits.
As an aside I bent a shoulder by maintaining very poor control on stops, giving me a saw tooth in the last 10m in a chop, admittedly this was after a 2nd deco dive of the day though.
Were you at Dorothea BTW, in which case the hill could have played apart, in between dives?
This was capernwray, going Dot on Saturday to play with the new lights a bit deeper.