Interesting, I've never seen that before. I like the thought of a gas/ebike being able to consistently cause enough heat to cause this, but I do know from experience that that amount of heat would have caused that lube to smoke. It would interesting to see a bike front wheel smoking down the road. Possibly a bike owned by that "Ghost Rider" guy.
I have "blued" various metals before but not something that was already properly heat-tempered and/or load bearing. There is a chemical "wash" that will give a similar appearance.