I wondered the same thing, are you sure it's not something with the bolt?
I would assume that the sizing die would've taken care of any bulges in the cases from the previous firing.
Especially a FL die.
Sometimes neck size only dies can leave cases a tad too big and be pretty snug on closing the bolt.
Is it all the cases you have on hand, or just a few of them that are acting up??
Aim small = Miss small