Ok, have to ask: WHY did you have shelf liner in your snake cage?? And I certainly hope it wasn't the adhesive kind. At times, those products can leech out things when wet. Learned this by putting some in my rat cage long ago. That may be the source of the sticky.

If not, then yes take the snake in to be checked out and see what's going on. Also, try and recall if he could have slithered through anything while you had him out. Lottsa luck.