My boyfriend has a reddit account and follows naked girls on it. I recently found out that he has direct messaged a few of them (maybe 4 messages total in an 8 month time span). The messages say things like "beautiful face, beautiful body, would love to see more" or "damn girl, where did those come from? keep them coming".
I get that guys look at porn and I haven't let it bother me in the past, but I am 100% grossed out that he goes out of his way to message them to let them know that he likes what he sees. This is creepy and not okay.

I confronted him about it and he played it off like it was nothing serious and it's not a behavior I have to worry about. He said it won't happen in the future (it hasn't happened for the last 2 months either) and it won't turn into something I have to worry about.

Background: I grew up with a step-dad who had a porn addiction and messaged girls to meet up with them. I have a fear that it will turn into that down the road if he's starting off slow now. Am I overreacting by wanting to end things over this or should I believe that it was innocent and it won't get worse?

Side Note: we have been dating for just 3 months so the last message was sent when we had been dating for a month.
We are both 28 years old.

Please give me some insight on what I should do. I'd really like to hear from people in serious relationships who dealt with something similar or from a man's prospective.