In reply to wjvt:
I occasionally get similar thenar muscle pump / cramp.
not quite a quickly as 10 min, but I think (not 100% because it doesn't happen that often) - it happens when I need to whole-hand grip things with baggy ill-fitting gloves.
you could try wearing thinnies underneath to fill out the box gloves. or try various means of holding things, use tongs or suchlike.
but yes, it happens and it's a pita.