Are you sure it's rolling over the thumb and not the fingers?  Do you see the oil track over the thumb hole or are you just assuming it's hitting the thumb hole because it's going "thump, thump, thump"?  Your profile doesn't say anything about your track, but if it's high 3/4, layouts with the pin under the fingers may flare into the finger holes.  --  JohnP

I normally track about 1/8 - 1/4 from the thumb.  I am going to try it a couple more games to see if I am holding on to it to long.