An older guy (in his 40's) introduced himself to me on the train. This rarely happens to me. My question is if a guy introduces himself or approaches you in random places is it considered flirting? Before you answer keep in mind it's one thing to speak to someone if they make eye-contact but to have someone go out of their way to introduce themself to you makes me wonder...
I think flirting is usually more obvious, however, a seemigly out-of-nowhere introduction might imply interest, yeah. I think a lot of it has to do with their body language and the language that they use when talking to you, as well.
