motiv girl and bowling mom,
you both need to get into the pro shop and have your spans and pitches checked, there is
absolutely no reason for any wear marks or burn marks on your thumb.
I bowl 20-25 games a week and I have none of those on my thumb.
make sure you thumb hole is the correct size, a lot of times you need some oval to make it right
and if the driller only drills it round it wont fit right.