Women, what would you do if a guy overheard your e-mail address in a bookstore and e-mailed you?

i've asked this in 2 other categories, but would like to get clarity from other women. i have not dated in years (was married forever). i gave my e-mail address to a bookstore clerk, and a man who had just complimented me overheard the e-mail address. when i got home 3 hours later, there was an e-mail waiting that said, "so, if a man overhears your e-mail address at a bookstore and writes to you, would that be stalking;)" i've received mixed feedback from men (everything from "psycho" to "gutsy"). is this bizarre or is this how people "date" these days? he is probably a little older than i am (maybe in his 50's, but was well dressed and articulate)...this has been a few days ago. i have not responded...baffled at whether this is the "norm" for men now. i would have preferred an "in person" conversation, not a "hijacking" of an e-mail address, but maybe i'm on the wrong thought track.