Has Lee removed the crimping section from their new seating dies? All of the Lee 3 die pistol sets I've used have crimping capability built into the seating die. If I'm using these instead of a Lee Factory Crimp die, I seat all the bullets, then back the seating stem out and run the die in far enough to crimp. I've tried seating and crimping in the same step, and while it can be done, it's not as uniform as doing them separately.
If bullets are seating really easy, you might have flared your cases too much. It's easy to do if you've been flaring to load lead bullets and then switched to jacketed bullets without adjusting your flare.
The real advantage to the Factory Crimp Die from Lee is not that it crimps, though it does. The advantage is that it also resizes the case again, removing any bulging that may have happened during the rest of the loading process, or so Lee claims.