Starting difficulty

About 6 months ago, on occasion, my car had to crank 5 or 6 times before it would start. I had it tuned and new filters installed about 2 months ago and it seemed as though the problem went away. Two weeks ago it started again. I took it to a dealer who said there was air in the injectors that was not bleeding out so the cranking was actually removing the air. It is doing it a couple of times a week now. It always starts but it is an un-nerving feeling. The car has 77,000 miles on it.