Ex Trying to Take My Man

So my boyfriends ex girlfriend messaged my boyfriend thru Instagram asking if there was a chance for them to get back together in the future (we've been together a year and a half now and she's known about me since we started dating). He replied no I have a girlfriend but she proceeded to say things like "But what if we were together?" Or "I can be yours". He blocked her right after but I still makes me mad. Should I confront her about this or leave it alone? She not only disrespected our relationship, but she disrespected me by knowing that he's taken and continuing to pursue him. I trust him so I'm not insecure about our relationship. I just feel like she's way out of line. I wanna just let it go but I'm not sure if it's the right thing. Any advice?