I inadvertently used PVC cement on some 1/2" CPVC pipe that feeds a
toilet supply. It held and it appears well sealed. Will this be a
problem?

It was inside a wall and I have already closed it up with new drywall

If you haven't painted yet, I'd still cut out the drywall and redo it.
Drywall is cheap, maybe $5 for a full sheet?

But, if you've already painted, put trim and cabinets in place, etc. I
guess you'll just have to hope for the best. It's probably highly unlikely
you would have any problems in the future anyway. The solvents work by
"melting" (or welding) the plastic together. Once it sets up, if it doesn't
leak now, I doubt it will leak in the future. But, you'll always have that
question in the back of your mind...

Anthony