No problem. I have done it a lot to previously checked and lubed bullets that I cleaned off to PC. For the PC to stick well, the bullet needs to be squeaky clean. My last step after boiling off the bulk of the lube is a wash with mineral spirits. Since yours have not been lubed, you only need to worry about what little residual lube from the sizing die that might have made it to the bullet or any other dirt or film that might hamper the PC. I'd rinse with mineral spirits and PC them. The gas check will be fine. BTW, I always run those through a sizing die again to smooth out the PC and bring them back to diameter.
