I don't have time to watch the episodes, but I reviewed the scripts for the episodes prior to ILTY.
Clark uses his x-ray vision several times in SV, but of course Lois isn't aware of it. I couldn't find any reference to x-ray vision in NB.
He also uses his x-ray vision - as Superman - in the Pilot where he finds Lois in the Prometheous and swallows the bomb. You could make use of that I guess if you wanted to. Perhaps Lois questioned him on how he knew she was in there, how he tracked her down, when he was flying her back to the Planet and he told her he had x-ray vision then. Could work.
But from what I could see it looks like a blooper from the writers or something that happened offscreen. Unless, of course, there's a reference on the filmed episodes which isn't in the scripts.
LabRat
