Okay, before you panic, many stores will take a camera out and fire a few test shots with it, just to be sure it's 100%. If they do, they probably have a compact flash card that's been in a lot of cameras and might have some other images on it, or hasn't been formated in a long time. The camera will start the numbering after the last file number that was on the card (in this case that would have been #1517).... Maybe.
Or, perhaps it was a returned item and has some clicks on it. Or a demo unit. Or a refurb. In none of which cases would it be acceptible for the store to sell it represented as a new item.
1500 isn't a lot of clicks. But it's the principle of the thing. If you buy a car that's a demo or was returned, it's discounted and not represented as brand new.
There are shutter count softwares that can be used with some Canon cameras, that would tell you for sure how many clicks the camera has on it. But I don't know if any of them work with 7D.