There's two possibilities : a mistake (the most probable) or the sender want his transaction to be proceeded really fast (maybe this don't make it being proceeded faster and thus this is the first possibility). This also may be just a dumb guy but it seems really probable to me, that's why I didn't included it in the possibilities list.
I agree completely. It definitely seems suspicious to me too. However like you said he might just not be too computer-savvy or coin-savvy
