Sounds like he was going to attempt to scam you, and then realised you weren’t going to fall for it and left.
There’s a lot of scam guides going round TikTok and other social media at the moment, I imagine some people are just starting out and don’t really know how to pull it off properly yet.
Probably tries it on a bunch of people and at least one they will be able to pull off whatever scam they are trying on.
Someone I know does a lot of agricultural services stuff where people pay with cash and encounters the same attempts time and time again, not to paint all tradesmen as scummy but he says a surprising number try the same old tricks to distract you while paying say a £1000 bill with only £900 worth of notes, etc. then play dumb if someone notices and/or claim you must have misplaced the extra £100 or trying to scam them if it is noticed afterwards, etc. and it is obviously not just a mistake when you've seen it many times.