Are you the original sled owner? That happened to me and it turned out that the p/o had installed an electric shield hookup, but had tucked it into the handlebar cover. One wire rubbed through and was shorting, since it took power from the headlight switch.
If it blows again, unzip the handlebar pad and inspect all the wiring, particularly the couple going to the hi/lo beam button. If nothing there, pull a headlight and check the voltage there for anything abnormally high(more than 14v or so). If so there could be a regulator issue.
Fuses do pop now and then like you said as just a fluke. Possibly from vibration, moisture, ect that fatigues the fuse and physically breaks the connection rather than from electrical load. It's pretty uncommon but can happen.