Airbubbles in radiator, normal or should I worry?

[twilightcall]

I checked the coolant level in my car today. It was a little low so I topped it off. I started the car and left the cap off. Once it was start I saw a bunch of small air bubbles come up through the coolant and the level went down a little. After about 10-20 secs. the air bubbles stopped and the coolant gradually rose back up. After that I saw no more air bubbles. I checked my oil and there was no coolant in the oil. Is this normal or is this a sign of a headgasket issue? How do you bleed air out of this system? I didn't see a bleed screw on the rad. or on top of the therm. housing. Thanks for the help.