my coparent ex hinted she "knows what i get up to" and i cant tell if she actually knows or is fishing

M40, divorced 4 yrs (amicable, mostly), shared custody 50/50 of one kid age 10. partner F38 weve been together 2 yrs, weve been in the LS as a couple for around 18 months. last week ex picks up kid for her week. small talk at the door, totally normal. as shes leaving she says with this weird half smile "well, have a good time on whatever it is you do on your weekends without [kid name]". and looks at me. like its a thing. and walks off. i was POLEAXED. i went back inside and replayed that sentence for 3 days. is she fishing?? is she genuinely just making a benign comment abt the fact that i have a life?? has someone she knows seen me somewhere?? does she ACTUALLY know specifically?? we play in a different city, we're not on apps shed see, we're very careful — but ex is a smart woman and she has a wide social circle. heres the thing that makes it worse. ex and i have generally been on good terms since the divorce, no court drama, no weaponising of anything. but she has a streak in her where if she "knows something" she likes to know that you know she knows. shes a low key intelligence collector by personality. its actually one of the reasons we split, that feeling of being studied. i dont think she would use this against me in any custody sense, like genuinely i dont believe she would. but she would absolutely enjoy the feeling of having ammunition she doesnt use. and she would prob make occasional little comments like that one for years. what do i do. address it ("are you fishing??") and risk confirming. ignore it (and let it sit between us forever). bring it up w my partner and start making changes to our setup. nothing??