Weird messages from guy

So me and my husband are happily married, together almost 10 years. About three months ago we were at Sam’s and we ran into a guy that he works with, they spoke for a few minutes and we continued shopping. A few days later the guy sent me and him friends request on fb, we thought nothing of it, both accepted him and moved on.

Apparently the guy and his wife got separated recently. I noticed he reacts to literally everything I share/ post. Didn’t think to much of it because I have some friends that do that. He started ❤️ all my photos then last Monday night, I shared a selfie (in the story thing on fb) he ❤️ 5 times (apparently you can like multiple times if it’s a story). Last Thursday I shared another selfie story same thing. ❤️ 5 times and commented “so beautiful” (if you comment on a story it sends it as a message) I said “thanks” and he replied “you are so very welcome 😁”. I showed my husband because I thought it was weird and he got irritated, I guess. So to avoid any issues I unfriended the guy.

Well yesterday he added me on instagram (my page wasn’t private until just now) and commented on a few photos “damn” “😍” “your man sure is lucky”

I thought dude was just being nice. Am I being naive. I have blocked him on instagram and made my page private

My husband said he is definitely flirting with me and he wants to say something to him but I said he was just being nice and to leave it alone. Thoughts?

Also to add this has caused no issues with me and my husband. I had no issues unfriending and blocking him. We trust each other fully.

To clarify I’m asking was this flirting? I haven’t been single since I was 19 and my husband and I were just having a debate about ( not a serious thing just kinda joking like)