Ordinarily the polyacrylamide gels are rubbery, but the ones I poured last week were very stick, and the stacking gel did not seem to solidify.  I was able to run a pre-stained standard, and it looked almost normal.  However, the gel stuck strongly to the glass plates and was unusable.  I made new acrylamide using a different manufacturer's bis-acrylamide, and the new gel behaved normally.  Either it was the bis, or I made some other mistake in making the acrylamide solution.  Has anyone ever seen something similar?  Any guesses about what could cause a gel to become sticky and less of a solid?

This is sounds like either incomplete polymerization or lack of cross-linking. This is often due to old APS or wrong acrylamide bis-acrylamide ratio.

The APS was fresh, but the first bis that I used was old.  There is also a chance that I made a gross error in weighing it out.

Considering that you manage to resolve your marker, I suspect that you got mostly linear acrylamide. Measurement errors could account for that. If you used powder, bis-acrylamide is relatively stable, but I do not think that I had a batch lasting longer than a year or maybe two.