Red flag?

Yesterday my boyfriend told me one of his friends got a new job as a regional director for a company and I said "Wow, that's really great" and then he proceeds to say "Didn't that guy you used to see work there?". I never told my boyfriend about him as that guy raped me and I'm still not ready to talk about it, and there is no way those two know each other or know someone who knows the other. Anyway I said "I didn't really date him but yeah" (because we didn't date) and my boyfriend asked me what his full name was so that he could make his friend fire him and I told him I didn't know (true, as we didn't know each other) and then he said "You must know since you've talked to him so much" and I was so confused and was like "No? I've never talked to him since I met him" and then my boyfriend says "Well, if I scroll down on your Twitter to 2010 there will be loads" and that made me feel a bit weird because I have written to him once on Twitter, indeed in 2010, only because he found me there and started talking to me and I told him to fuck off and then I blocked him. The thing is that was three years before my boyfriend and even met. It feels a bit creepy if he has stalked my Twitter that far back because I tweet A LOT. Is this a red flag or am I just over reacting?