Antheia - It depen on how strict you are being really I suppose. If you eat any food you dont prepare yourself, then it shouldnt amtter really.
If you visit a busy subway for example, their product turnover is such that it shouldnt be a problem, because the product they are using isnt old. Your local ma and pa milk bar that doesnt sell too many sndwiches may use older product.

So long as it is washed it doesnt really matter. It just comes down to personal choice I think about how padantic you are about it.

Oh, and meat can be cooled and reheated twice. (not including cooking)