It sounds like you were playing OFC 2-7, where the middle row is the best low hand, and anything over a 10 low is a foul. Thus a fullhouse would be a foul in the middle. Check your hand history to see if this was the case.
No, I think he talks about a real but minor bug in the high variations.
To be more specific, let's say that we are in fantasy land with the possibility of setting two full houses with AAA, KKK, 99 and 22. If we place AAA22 at the bottom and KKK99 in the middle, the "foul detector" reacts and invites us to place AAA99 at the bottom and KKK22 in the middle. It would therefore seem that instead of taking into account only the rank of the trips it does it for the rank of the trips and for the rank of the pair.
I have already forced this situation to see if the hand actually ends up being invalidated and it is not. So this is just a minor bug.
Fernando is correct, this occurred while playing OFCp Progressive, not 2-7.
I set a FH on the bottom and a weaker FH in the middle. When I clicked the "Play" button, I was prompted with the error message stating that I was going to commit a foul if I continued. I ignored the message and continued without issue; the hand did not actually foul.
On one occasion I did witness another player change his hand construction because he/she was afraid to risk it. It may be minor bug, but it certainly has cost some players a little bit of money. But again, if you ignore the message and play your hand how you intended, nothing will happen. Unless of course your hand actually is fouling.