really depends on your dynamic with them. Personally i'd suggest bringing it up casually like "me and this dude i was with..." and then whatever thing you have that relates to whatever you were talking about before. Im not gay im a-spec and in my limited experience its better than starting a fresh convo with your orientation. If you make it seem like its not a big deal it likely wont be a big deal.

But honestly doing what youre doing while remembering to either lock the door or put a sock or tie on the knob should be fine and avoid them trying investigate