@midwestflow wrote:
I did put the partial number on the listing.
I would just tell her that it's in the listing, then. Posting a photo of it as well would be a good idea. It may be that she's reading the listing on a smartphone and hasn't even seen the description.
She can't really report it as stolen just because she has the serial number in advance of the sale. There's a whole lot more to reporting a stolen item than just that.
EDIT: Okay, I just noticed where you said the number shown is a "partial." Obscuring the full serial may or may not be needed; usually not. Assuming it's the bike, which is New In Box, and you know it's not stolen, I see no reason not to provide the serial in case she wants to verify that for herself.