As a seller you have given more information than you needed to. If you were aware the bike was on the hit list then by law you need to inform any potential purchaser, however either the bike wasn't on the list or you didn't know. By telling them it has been damaged at some point means the onus is on the buyer to thoroughly check out the bike. I assume you did two receipts, one for him and one for yourself, stating Sold as as Seen. If so then you don't have anything to worry about, both on a legal and also a moral level.