Definitely worth a conversation.
I would agree with the previous poster, the old me, who had not been cheated on, who had not been through multiple years of counseling, and all the other shit, would have considered this rather innocuous. On the face of it, it does look innocuous.
Unfortunately, sometimes it is somebody else on a fishing expedition.
A few years ago, years and years after the affair and D-Day, after counseling had ended, when things were going fairly well, I kept getting a message on my email generated by Facebook because I had an old Facebook account that I did not use. So I went on Facebook after several of these came through, as the person lived in the same town, where I worked, although not where I lived.
It turned out that this was my FWS's boyfriend from high school. He had moved to this area, which was the town that she grew up in, although not where we lived. He had also contacted her through Facebook, which he would've easily been able to do so as the community is quite small where they are from. They had become Facebook friends. He had gotten divorced, and on his interest he clearly stated he was "interested in women".
She had never told me about this FB request and link up.
None of her messages were inappropriate. None of his messages were inappropriate. But this is a guy she used to fuck. This is a guy she used to "party with". He was clearly divorced and looking.
I had a very firm conversation with her about this. If she had learned anything, from 4 years of MC, she would've informed me immediately if an old sexual partner reached out to her.
The fact that I found it out because of some software in the background that tried to link everybody up, only because I had an old Facebook account that I had intended to use for business, and decided not to use because of the potential for just this sort of thing, and not from her was a problem.
I was ready to leave her, divorce, end the marriage. I told her I was just fine with her being friends with anyone she wanted to be friends with, but then I was not fine with being in a marriage with her if she was linking up with old boyfriends. But I was also not fine if she was getting messages from old boyfriends and not telling me about them.
I didn't have to threaten her, she blocked him, defriended him on Facebook, and went through her contacts, making sure there wasn't anything else that might be concerning.
She did say that she "didn't think anything of it", I pointed out that she "clearly were not thinking about me" when another guy contacted her.
She has gotten frustrated over the years because of the fallout from the affair. But I did not have the affair, I did not lie to my spouse for weeks while having sex with somebody else, I did not lie to my spouse for years and years and years afterwards, and I did not lie about my spouse and to my spouse in the counselors office for over six months before confessing for real.
So I would have that conversation with my spouse, if it turns out that this person is an old, romantic partner, you will need to have an entirely different conversation.