I put a spill free funnel on radiator and filled funnel with coolant. When it got to operating temp I was seeing about 1 tiny bubble every 6 seconds. Is that normal or should I be concerned?

 

Without a cap installed, some boiling will inevitably spill out of the cap. This is what happens when you boil anything.

Head gasket leaks are usually more pronounced. You can smell exhaust, and when you hit the throttle, the amount of aeration increases dramatically, usually to the point of making a huge mess.