Should I tell my husband??

So I just had our second baby a week ago. My husbands old coworker that moved away added me as a friend on Facebook last night & I accepted it around 1am when I was trying to relax after putting our fussy baby back to bed. He messaged me almost immediately after. We (being all 3 of us) used to hang out together all the time. He’s super into gardening & help us build one in our backyard 3 years ago when my husband & I moved into our house.

He was my more my husbands friend than mine. They spent more time together because they usually worked the same shift but whenever we did talk it was always pleasant.

He moved out of state about a year ago & they kinda stopped talking for a bit just because life got in the way.

Anyway, I replied back but he was just acting... weird? His part of the conversation seemed very flirty. I ended up falling back asleep shortly after I realized he was acting weird. I woke up this morning to a message he sent shortly after I fell asleep saying “can I confess something?”

I just typed back “Sure. What’s up?”

He replied back just now & said “I probably shouldn’t tell you.”

I tried to pry to see what he was trying to tell me but he just changed the subject. I don’t know if I’m just reading too much into it? Should I bring it up to my husband or just leave it be?