I load military 9MM brass on my Super 1050 and have notice the same thing however, it doesn't seem to cause any problem and the next time I load the brass the decaping pin knocks out any small burr over the flach hole.
If I'm loading commercial brass, I use a non-Dillon expander and avoid any potentional problem.
When I load .40, I don't use the Dillon expander either because it bottoms out on the web of the case about the same time you get a good bell.
With .223, I size/deprime, swage the primer pockets and trim using a Dillon power trimmer. I then tumble the brass to remove the lube and then use a Redding neck size bushing die without a bushing (you could use a universal depriming die) to insure the flash holes are free of burs and tumbling media.
LIZARD OUT