Well, I just bought an '01 factory set and opened it. I believe that the cards were meant to be seen and appreciated, not sit permanently closed up. Much to my dismay, almost all the cards were stuck together; the entire set was a brick. Tried a few tricks to get some loose, but the ones that came off were tore up; total loss. As been mentioned, this was common for Topps factory sets in the late '90s, early 00's. I'd been lucky to this point as the runs from 87-02 had been fine except '94 and '01.
With that said, if you pull the '02 set from the sheets I'd store them in a box, but don't pack them too tight. That is how the factory sets run into the sticking together issue. As long as they are packed more lossely and climate controlled they should be fine.
My sins have come to face me, I can feel it
That I have lived my life in vain
And now I know I'll reap the seeds I've sown