Hi there, yes it is common, I had to go 3 times before the lesions showed up. Are you saying that you have been feeling fine for 4 years? I would think that in 4 years without being treated, etc that your symptoms would have progressed to some degree.
Yopur are right - no one likes to wait for their results, but you should go and get another one done just to see what is going on. I mean, you have waited 4 years, whats another couple of weeks - LOL
Have a good day