A few days ago my cousin told me that if I keep my plastics in Plano boxes, then the boxes can warp. Is this true?

I had some that did, but those were early boxes.  I believe most manufacturers today are aware of the worm problems

and have adapted there boxes to accomodate worms without warping.

I haven't personally seen it I just moved all my plastics over to trays to get them organized so hopefully I'll be in the clear as well. Downeaster I think your dead on I think it may have been an early issue, if nothing else I hope for my sake.

_{Yes. The tops warp badly.}

Most current plano boxes do not.  Earlier ones-I cannot speak.

I have several Plano boxes that have warped, the front of the lid bows and the corners lift up in a "smile".  Some of these boxes are for cranks, some jigs, some plastics so I don't think in matters what is stored inside.  I've noticed it mostly on the yellow latch Stowaway boxes and no so much in the CDS Stowaway boxes