Yea, I think if it really bothered me at the time I would say something , casually like though. If I didnt say something at the time I would leave it though, I mean it would be kinda weird to then say "who was that guy you said hello to 3 days ago in the pub"
There is of course the possibilty that she has bought some hash or something off him. Could be an aquantance from drinking in the same pub......I used to say hello to a guy who used to come into the Nightclub I worked in. Used to chat away quite the thing, charming guy, used to talk about fishing......about a year later someone told me he was a shady gangster! LOL you never can tell