Buyer declined offer but then purchased full price Buy it Now

[tlc_treasure_trove]

Has anyone had this happen to them? Buyer sent an offer, I sent a counter offer. They declined my counter offer but then clicked the buy it now option and paid the full price.  I kind of feel guilty. Can I or should I offer a discount even though they already paid? Can I even give a partial refund before shipping? I just do not want some issue coming up later. 

Thanks!

[rfmtm · Accepted solution]

If buyer isn't complaining for their mistake, keep it simple and process normally, don't create an issue yourself.