From most/many places in California you can see an occasional launch from Vandenberg, which is very interesting, and can definitely be mistaken for ufo's. My parents have definitely done that.
A UFO is an Unidentified Flying Object, which means anything that you can't identify is a UFO. Many people use the term "UFO" when they actually mean something else.
I see many UFOs all the time. I know they're UFOs because I sure as hell can't identify them. But I'ma also pretty sure they're not extraterrestrials here to butt probe me.