I'm not really sure why some boxes get distorted,while others don't.It could be because of the climate,or possibly stacking other kits on top of each other.I have sealed kits from a while ago,that look perfect,like the day they were made.While others look like they were left out in the rain.As far as opening kits while in storage,that all depends on the kit.Is it a rare expensive kit,or just some everyday kit you can buy anywhere.My advice is to keep the kits sealed.You should also store kits,wether they are open,or sealed,in a dry environment,and try to buy kits from homes that are non smoking.