Well, I think that in the show Smallville his powers are just developing right? So maybe he hasnt gotten the full "stone skin" thing goin yet. I seen a couple episodes (Love that Kristin Kruek) and he is just getting some of his powers. Like in one he had just gotten his heat laser eyes thing, in another he started flying (sorta).
So, pump that needle in him in a year or so and see what happens?

Maybe tonight we'll fly so far away... We'll be lost before the dawn...