I agree 101% with the probablity of your using, perhaps, too much lube. Another poster added the cleaning/opening if necessary of the air bleed hole. A third possibility, which has not been mentioned, was demonstrated by a friend (Steve) years back when he had a similar problem as yours and asked members of our Bullseye group for a solution. After adiving to use less lub and make sure bleed hole is open, the problem remained, but not as pronounced. He was asked to bring suspect die to next week's match, and without any real checking, our senior "sage" dropped the die into a mason jar he had brought with a solvent (gasoline? lacquer thinner? (I do not recall)) filling it. We shot for about an hour, after which Carl removed the die and brushed the innards quite aggressively with a soft bronze brush. He reassembled it, put it into the single stage press bolted there, and sized about a dozen cases with zero dents or irregularities. I do recall the die brand -- Lyman -- and apparently Steve purchased it, brand new, and had not cleaned it/removed their rust-preventing coating!
You did not indicate if your die is a brand-new not cleaned one... If so, here's another possibility.
geo