The boxer engine should never be warmed up before riding. It is best to get your gear on, mount up and start the engine. Move the bike off the center stand, engage 1st gear and ride off...no warm up.
There have been instances of boxers catching fire by owners who made the same mistake...starting the engine, leaving it running and getting distracted.
You were fortunate however, you may experience some heat related problems in the future (seals, oil leaks, wiring damaged, etc.).
I would inspect the engine oil for signs of overheating and change it if found to be suspect.