What could one do with my serial#?

[roadie1]

I had a watch for sale here on the forum. A gentlemen was ready to close the deal on my watch after at least a half dozen emails of photos, etc. he wanted to see the warranty card, tags, etc. of course I obliged. My serial number was clearly visible in a couple photos. Then he disappeared without responding to any other emails. I'm fine if he bailed as I've decided not to sell the watch at this time. Afterwards I noticed he was a new member with zero post. Could he use my watch serial number to fake another watch? Am I being paranoid?
Thanks