I remember this one distinctly, this creeped me and my roommates out.
My last year in school I lived with 2 other guys in an apartment, they shared a bedroom and I had my own. It was during the week, school night, normal, chill, nothing out of the ordinary, I went to bed, blah blah but at 3 or 4 in the morning, I distinctly got woken up by the sound of their doors opening, closing, footsteps in the hall and then the front door open and close...i was like...wheeere the fck is this guy going at 4 in the morning? and it was unmistakable what I heard cuz I've heard the same doors being opened and closed hundreds of times. Sooo the next day, I casually brought it up, it wasn't a big deal, i was just like "did one of you leave last night? where were you going at 4 in the morning?" They just looked at me with blank faces and was like "wtf are you talking about...we didn't go anywhere"....so I was just like huh guess I must have dreamt it and told them I thought I woke up to the sound of them leaving...they just looked at me with a weird face and was like "that wasn't you?... cuz we thought you left cuz we heard you walk out..." and they weren't messing with me.
We lived on the 5th floor so the only way into our apartment was thru the front door with a card key that only the 3 of us had. And we would have heard someone come in, but all we heard was someone leaving and it wasn't even rushed, it was non-chalant and casual walk-out speed...so i doubt someone was actually in our apartment without us knowing. The other strange part was that I clearly heard their bedroom door open when they claim to clearly have heard mine, and there wasn't another door in our apartment except for ones in the kitchen, but that's in a totally different direction. It was just a total mindfuck and we couldn't figure it out.