If you didn't switch items, and if you didn't steal anything, and you do have a receipt that matches your purchase...then you're acting awfully paranoid just because some store employees looked at you while you were leaving.
(And regarding opening boxes, I have found that the size tag on the underwear inside boxed women's underwear very often doesn't match the size showing on the box. Sometimes the colour is wrong too. I have no idea why this is, but I have learned to always open the box and check the item inside the box before deciding whether or not to take the item to the cash register to pay for it. Saves me a huge hassle - which I had to undergo several times before learning my lesson - of having to pay for the item, go home, find out that what's in the box is wrong, return to the store, go through an enormous amount of explaining, get an exchange note, only to find that the item I want isn't there. And then more explaining to get my money back. Easier just to open the box at the beginning. Just sayin')



