Nobody's calling you a liar. You saw what you saw, and that's pretty much that. I think the problem is that since the ghost/lens flare incident had a perfectly logical explanation, many are quick to dismiss this story as another example of a natural occurrence drawing suspicions of alien/paranormal activity.
Seeing something that we are so often told doesn't exist will often trigger a "no way, that shit was totally for real" reaction in our heads, because we secretly want these things to exist. Everyone knows that the flying spaghetti monster doesn't exist, but if you saw it, you'd shit your pants in awe. You wouldn't think "Gee, I might be hallucinating right about now." You'd be thinking "OH FUCK ME WAIT TIL MY FRIENDS HEAR ABOUT THIS."
I was doing some research about alien abductions, and how a lot of them seem to follow a very similar storyline or may even contain the same alien race/species. Right away, such continuity would likely lead many people to believe that alien abductions are pretty legit, because presumably, none of the victims would have talked to each other prior to the event. However, a similar phenomenon exists in
sleep paralysis. Victims often experience a vivid hallucination of a demon or perhaps the devil himself pressing down upon his or her chest, rendering the victim unable to move. Such hallucinations can occur without any prior knowledge of the phenomenon.
People hallucinate every day of their lives, be it through dreaming or something else. Traumatic or high-stress events can be powerful catalysts to hallucination. Seeing something that looks a lot like a flying saucer could very easily trigger the fear reaction that movies like War of the Worlds and Invaders From Mars have taught us to obey. When the fear kicks in, you are quite unlikely to consider the logical causes of the flying saucer.
Hell, I've seen a UFO before. There were three blue lights in the sky, just sort of hovering there. They quite resembled what I assume the underside of a flying saucer would be like. As I drove home, I noticed the lights were emanating from the university football stadium. Lo and behold, they were testing a new lighting system. No flying saucers here.
Whether witnesses of UFOs look for it or not, there is likely an explanation.