I am not sure it is that unusual.
Happened to me on a flight last year on a not too warm day in Southern state. At cruise height was maybe low 20's C. IPad strapped to my thigh and in sun.
I held back of it up to air vent for a couple of minutes and it was ok again. After that just shaded it from direct sun.
Still, I also have a hand held Garmin that is not running but can be up and running rapidly as back up.
Interesting that yours was about 10c ambient.