PM sent.
I never understand why people post stuff like this. It's utterly redundant. I see it on Facebook all the time too. Literally no need to post publicly that you've PMd someone as they'll get your message (and if it'd to do with sigspam then you wont get paid the post on bitmixer because it doesn't meet the minimum requirements so what the point?).
The reason can be to warn OP. Sometimes people starts a thread buying/selling sth. Then they get some pms but dont return senders even if they are online. So the purpose maybe publicly notify or warn.
Yeah, I have send him a PM and did not get any reply. I commented to give him a notification, if he does not see or missed my PM.
He only started the thread an hour before you posted and it was the last post he made today. People need to be given time to respond but private messages are usually the first thing they see when they log on and respond to so I could only understand your logic if it had been days and no response even though he'd been online or posting.