Apart from a cousin I (25M) have met maybe 2 people who stutter. One i met when i was a teenager and he made me extremely uncomfortable, probably because he reminded me of my own stutter. Another guy i met recently, i wasn't really uncomfortable with him but still i didn't bring it up. I wasn't sure if how he would take it. So i think unless you get to know him better it's completely fine if you didn't bring it up