wife came home from solo girls night with a hickey, we are LS-adjacent not poly, am I overreacting

context first bc this matters. been together 12 years, married 7, opened things up like 18 months ago. we play together only, soft swap mostly, very very rarely full, and we have a clear rule that solo play is not on the table. its a swinger setup not a poly one and we both agreed to that twice in writing basically lol. saturday she went out with her two best friends, both in the lifestyle too actually, to a bar in our city, no couples thing planned, just drinks. came home at 1am which is normal, slept on the couch saying she didnt wanna wake me which was a little weird but ok. sunday morning I see a hickey on her collarbone. she sees me see it and just goes "oh god I forgot, some guy at the bar got handsy on the dance floor, nothing happened I swear". ok so... nothing happened, but also a stranger got close enough to leave a mark and she didnt tell me when she got home. and she has two friends who saw the whole thing and havent texted me either. Im not freaking out outwardly but my chest is tight and I dont know if Im being a controlling weirdo or if my gut is reading this right. she has never lied to me as far as I know. but also Ive never had to think about this before. how would you read this. is the hickey the issue or is the not-telling the issue. how do you bring it up without nuking a good marriage over a possibly innocent dance floor moment.