For years I've always kept my plastics in the bags they came in and stored them like that in various ways. But for Christmas I got another smaller tackle bag and decided I would move some overflow plastics out of the bags into the Plano boxes it came with. They are the 4600 size and are stored vertically in the tackle bag with the shorter sides down and up. Because of gravity, the plastic worms I've got in there aren't sitting very straight when in this vertical position. My worry is that over time, these plastics will get odd bends and twists in them. Is this a legitimate concern or am I worrying about nothing? Someone please ease my mind...

That's how I store my plastics. Never had a problem.

it probably would depend on he temp you keep the boxes in.

For plastic worms and stuff, you probably won't ever notice any deformities. You'll be fine storing them like that.

The only issues I ever had with putting plastic baits in those boxes were swimbait tails. make sure you get them in their straight or they will run weird.

I have everything else jammed in there... some even over filled and everything else works just fine.