I noticed the thumb holes on these balls are getting clipped, my spare ball and my low flare balls. My pap has changed that's for sure cause even the track is getting closer to the fingers by half an inch.  --

The change in location of the track doesn't necessarily mean that your PAP has changed, more likely that your axis tilt has changed.  Put a piece of white tape on the PAP location you've been using and see if it indicates a change ( be sure to get someone else to watch it off your hand to get an accurate indication).  --

It's been a while now, about 4 to 5 years since I had my grip checked. During that time I've taken a year off and my body has changed in size. Likewise, so has my game somewhat. --

Your spans most likely haven't changed, the size of your fingers may have.  What's changed in your game, speed, revs, hand position, etc.?  --

Does my grip need to be reevaluated?  --  Absolutely, everyone should have their grip checked every couple of years.  --

I bowled on a medium-heavy volume condition last night and my solid medium ball was flaring over the thumb. Should I be concerned?  --

It sounds like you were staying behind the ball more, decreasing your axis tilt.  If so, a hand position change should get you off the thumb hole.  --  JohnP