Creepy sightings

Out of curiosity, has anyone ever have a creepy sighting that makes you think you saw a ghost or something supernatural even though it is not physically possible? How did you react? I am not talking about dream hallucinations, but situations that happen during the day when you are wide awake. I have one example I can give. It was back when I was a freshmen in college. I was walking on the indoor track above the gym in the middle of the day. Some of the lights weren't on so it was semi-dark in the gym. Not too dark, I could still see where I was going and my surroundings, but it wasn't very bright either. I was also all alone in the gym. Well, as I was walking around the gym listening to music, I just happened to notice a figure standing on the college Red Hawk logo in the center of the basketball court.

I noticed whatever, or whoever it was, was facing my direction, and then turned toward a doorway leading out to the lower level hallway. From that point, it bolted through the doorway at a very high speed. I quickly ran to the steps where I thought whoever it may be would come up since it led right to that hallway. No one showed up. And there is only one upper level hallway and one lower level hallway and both are very short and the lower level entrance is within a few feet of the stairs. I did not see or hear anyone leaving the building, or heading to the weight room right across the hall or even coming up the steps.

Feeling somewhat confused and creeped out, I quickly gathered my belongings and left the gym immediately. I did go back later that same day though when there was more people there and all of the lights were on. I felt dumb for reacting that way and I don't believe in ghosts personally but at the same time, that was one situation that made me temporarily wonder. The thing that made it more creepy, and rather sad too, is that just a few months prior to that, the basketball coach collapsed and passed away right on the college logo in the center of the court. The exact same spot I saw the figure. I didn't see the death occur, although I had just missed it by a few minutes that day. Even though I didn't know him personally and may have only seen him a couple times in the halls, I still avoided going down to the gym for several days after that just due to the awkwardness and sadness of the situation.

Due to this, it made me wonder if I had seen the spirit of the basketball coach. I know that is really impossible but that was a instance that made me wonder. The other possibility is that it was a random student there acting really weird and must have hid or something which could explain why I didn't see or hear anyone leave. In the case, what was the student doing and why was the student there. That is something I'll never know if that was the case. Is there an explanation for what could cause these kinds of creepy experiences and why? Do you have any experiences you would like to share? Just curious. It is one of those cases that baffle me to this day. It never happened again but it did temporarily creep me out.