Get yourself your own that is a different color or type, etc. than the store's and know it is with you at all times (but leave it at the store at night)? Might make you more comfortable from seeing the others since you would have "yours"/be carrying them around. I'd get a tool belt :-) and holster for the box cutter so you have somewhere to "put" it when others are around and don't look funny just constantly holding it?

http://roadietools.com/holsters.html