But since the government says it was a jet contrail, there is now reason for skepticism. :)
How many airliners do you know of that are capable of a vertical trajectory?
It was an exception to the norm. If what you are saying was the case, then it would not have made the national news. There are plenty of aircraft that fly around Los Angeles everyday. We would see what is here everyday and we do not. Thus, why we see what we see.