No, it's not "normal", Chris, but it is not uncommon. How old is your three jaw? If it has seen a lot of use the
jaws can wear, sometimes at the ends, and sometimes the wear is in the slots in the jaws where they run in
and out in the chuck body. I have a few chucks. One is a rather low cost import and after just a couple of years
of use it shows such wear.
Hopefully it is just some wear on the gripping surface of the jaws themselves. In that case, you can grind them
true, but that practice does remove enough material that the jaws may not quite meet in the middle. That too,
can be ground to make the jaws meet, but you are getting into a bit of work there. If the sliding part of the jaws
are worn, it means the jaws are "tipping" outward when you tighten them on a piece of stock.
Dean