^Yep fairly normal. They should collect into a larger bubble, hopefully in the res. If the bubble collects in the rad, it will hamper the cooling ability, so its worth tilting the system a few days afterwards to push those out.
Just leave them alone. They will eventually move their way into the res or the rad (not the best place for them). By draining and refilling, you are simply recreating the issue...just be patient, give it a week or so and see where they are collecting. If you don't see them in the tubing or the res...assume they collected in your radiator...time to move them around and force them out.