As to how " standard " output protection is, I couldn't begin to say, I just know it exists and is more common than we would probably think. As to which amps in particular and how many in modern production there are that do, I have no clue.
If you didn't see smoke, or a light show coming from your amplifier, the odds are really good that no damage was done. In many cases, you will hear the self-destruction occurring as the OT starts going into meltdown and your tubes try and not do the same.
Truth be told, it is really only a problem if you do it for a particularly long time, and or have your amp literally turned up to 11 while trying to play. The build up of voltage is largely a part of how loud the amp is set to play. Most individuals don't really use their amp at a setting that is all that loud in comparison to what the amp is capable of. Keep in mind that each +3db of output requires 2X the amount of power. So if you are playing at bedroom levels with a speaker that has an efficiency of 98db at 1 watt, 1 meter, you are probably only utilizing 1-2 watts of the amps potential power. This would mean you would be playing at around 98-101db in your room. This is not even going to make the needle move in terms of the amps potential. Conversely, if you play at 11, well, disaster will be swift.