Lube on the shoulder is not a problem. Too much lube on the shoulder is the problem. If you get lube dents make a note to use less lube next time. The dents don't matter. they blow out when fired.
I'm also guessing that due to the method of how you tumble yours; There is no excess lube anywhere, or if there is it could be quickly wiped off while processing. I tried to dent a case (for science) with my lube (thick Hornady Unique). There are relief holes in the die I tried, which allowed a worm of lube to escape without denting the shoulder.


















































