In my experience it is a typical problem. Post screws are sourced by the OEM "off the shelf" and have no custom specification for the smoothness of the ends. The sharp excess is a result of how the threads are rolled on the blanks. That's why for new attys with cross drilled posts I always sand the ends as part of the initial set up. It's a bit annoying but not difficult. You just need to take down the really sharp edges. Holding the screw by the threads with smooth needle nose pliers works fine, though it's a little fiddly.
I made a little aluminum jig that works better. Imagine a tongue depressor with a hole drilled in one end the size of the screw OD. Pop the screw in, put your index finger over the head, and work the underside over a piece of sand paper sitting flat at the edge of a table. Goes quite fast that way and not fiddly because the screw holds its position. Now, come to think of it, an actual tongue depressor would work fine too.