Is it normal to get minor focus problem with contact lenses?

hi guys.

I have been wearing glasses for the past almost 9 years, and recently purchased contact lenses. The thing I did gain clear vision with lenses, but it gets blurry, or gets out of focus for short amount of time. The only way to explain how it feels like is that imagin your taking a photo, and your camera lense is not understanding where to focus on so it keeps getting clear and blurry back and forth (but not to fast) sometimes when it feels like my vision is unnatural, and I check each eye sight, either one's vision is clear or blury so I have to do that "massaging your eyes" or "blinking a lot as if it's going to somehow clear your vision" thingys. According to my doc, he says it's perfectly normal, but other people don't experience such problem that often, is this natural? is it ever natural to lose focus once in a while with contact lenses? or you shouldn't have any problems with having clear vision?