On petty theft

So I needed boxes for my upcoming move (If you're one of the three people who actually reads this thing, I imagine you already know, but just in case, I'm moving all my stuff into storage and taking off for Europe for three months), and after visiting seven different places and not getting anything, I finally pulled to the back of Wal-Mart. There were a bunch of crushed and unusable boxes, but there were also some that were stacked nicely along the wall. On them, they said, "RETURN FOR CREDIT. BOXES COST WAL-MART AN AVERAGE OF 75 CENTS. DON'T THROW AWAY." I took 10. That's not stealing, is it?