I think snopes is pretty reliable when it comes to this sort of urban legend.This has been around for a while. It is false according to snopes. While I usually disregard snopes as a reliable source of intel, just the fact that it came to the attention of snopes says a lot about the story.
My wife regulars that store with two kids the the right age description so you had me concerned but this piece is written like a typical Facebook terrorist.
ETA: Bill beat me to it