Shit happens. That's has to be from edge build up. I pull the reamer and check it and remove edge build up gently with a fine diamond hone before going to final depth.
I have not but I had it happen on a rifle I had built. The gun shot a .2MOA group but the brass had a bunch of little ridges in it from a messed up reamer that the gunsmith used. He fixed it at no charge.
I dunno how everyone else does it, but I shut off the flush system when I get to the point of using feeler gauges for final depth.
Plug the barrel with patches to stem the flow and take a little extra time to inspect reamer/chamber that last bit.