I don't see any red flags but the seller doesn't show a pic of the creed and there's an inconsistency in her description.It was also suggested to me from this forum to look at Bonanza for vintage Coach bags.
http://bags.bonanza.com/booths/live...12_USA_Vintage_Wool_Tweed_Demi_Zip_Top_Handba
Coach H9C - 6112 USA Vintage Wool Tweed Demi Zip Top Handba
seller = liveluv
The title shows 6112 as the style (which is correct) but the description has two different serial numbers mentioned.
Also, I'm not sure the bag is correctly described as vintage. It's from 1999 so it's 12 years old.
Please request a photo of the creed.
In the past, the seller had listed a fake Coach bag on Bonz. I haven't seen any fakes since: http://forum.purseblog.com/ebay-forum/bonanzle-fakes-421522-147.html#post15631668