Would he check a set twice to you? I would think that on the flop that if he had a set then checking to the PFRer would be almost standard, but on the turn I dont think he is going to check again. Could he view your turn bet as simply a delayed continuation bet? I think this could be air very often which would make raising fairly pointless, I just think this line is a little weird for a set, Im not sure what I would put him on really.