Any number of things could've happened with that deal, including more-recent message notifications being near the top of the drop-down notifications... hence, the seller saw his message before yours because his was later. It's also possible he saw responses in the thread before he read any messages.
Ultimately, who the purchaser is comes down to the seller's decision. If you had two-way contact and had reached an agreement only to have the seller stiff you, that's just crappy behavior on his part. On the other hand, if he saw the other person's message (or thread post) first, replied, and had reached a mutual agreement with that person before he even saw your message, then it's nothing more than bad luck. No evil, malice, or ill intent involved. You got bit by the board... drop-kicked by a drop-down. It's no worse than being outbid on eBay or walking up to a swap spot and discovering that NOS dash pad is already sold.
Regardless of circumstance, is this really federal-case material? Is it worth creating hard feelings between fellow board members over a couple of pieces of steel, whether it's just the other two guys involved or dividing the whole forum into factions? Not in my book... hell, I don't even think it's worth the increase in your blood pressure. Life's too short.
