You may be alright, especially since it's been cold lately and not in the upper 90's here in SoCal!
If you have air in the system, most times you'll hear a gurgling sound when you turn your heater up to max with the rpm around 2000. If you hear this, you've got air!
Easiest way to get rid of that air bubble is to park the car with the front end up in the air, put the heater on (to flush the air outta the heater core in the car) and open the radiator cap(do this when the engine's cold!).
Let the engine come up to temp and watch for the thermostat to open. As soon as it opens, you'll see the water get a little bubbly and start moving. I like to rev the engine up s l o w l y to about 1500 rpm a few times while I'm doing this just to get it moving a bit.
Hope that helps!