My "check engine" light turns on....
In retrospect, I don't think that was the problem at all. If the bike was overheating, wouldn't the "engine temp" light have come instead? I think that, perhaps, with the heavy load on the bike, the engine didn't like being lugged along at 60mph in 6th gear. Perhaps I'll never really know because I turned the key and, hallelujah, no engine light--we're back in business.
I've taken my bike to the shop to determine what the "check engine" light was for. The bike computer came up with code #18. The tech said, "let me guess, you were lugging the engine at highway speeds when it came on." I was. It turned out to be a signal for my missing XSUP motor, which is a piece of worthless smog related equipment that I removed. Counselor said I didn't remove it properly, so it threw a code. Nothing was ever wrong with the bike.