Did I Damage My Head Gasket--1998 E300

[RLGDiesel]

So I need some reassurance that I didn't turn a minor repair into a bigger one this weekend...

Story: I changed the thermostat on my 1998 E300 a couple days ago and lost a lot of coolant in the process. I refilled the expansion tank with about 1 gallon and restarted the car with the cap off. I planned to let it run for a few minutes to let any air in the system out. When I walked to the front of the car, however, I noticed coolant overflowing out of the top of the tank. I capped the reservoir instinctively because it was making a mess on the garage floor. I let the car idle for several minutes until it reached 78-80*C since I was mainly concerned about leaks. At that time the heater was still cold and neither the upper and lower radiator hoses were hot either.

I realized I still had air in the cooling system, so I let the car cool down overnight. I woke up the next morning and started the car with the cap off. The coolant stayed at full until I revved the engine and held it at 2000 for 2-4 minutes at a time. I refilled the reservoir repeatedly during this process until I added another gallon to the system. The temperature never got above 90-95 during this process (higher than normal but not dangerous per gauge).

What I'm worried about are the ~10 minute periods that I ran the car with air bubbles in the system. Since the expansion tank stayed full before I revved it and I later added another gallon, could the aluminum head have been running with only 2 quarts of coolant and mainly air for a brief period. As I read about proper bleeding procedures, I also heard about head gasket damage caused by "hotspots," "air pockets," and "cavitation." I didn't want to save a few bucks doing this myself and end up damaging something because I don't have the same vacuum fill technique as the dealer.

Thanks!

Luke