Should this concern me? Photo theft?

[emill]

If you said it as a product shot of skateboard wheels, I'd do a search of them on eBay or even a google search of skateboard shops and check the wheels on that site. Seems like a lot of merchants, on eBay at least, will use stock photographs, especially if they use multiple auctions.

[Broseidon]

I personally wouldn't worry, but do add watermarks on your images. I need to do that myself.