I'm not surprised that it started at that temperature without glowplugs. Often I would simply twist the key when starting a vehicle, then I would hear the sound of a diesel. That was only the case when dealing with a computerized direct injection engine.
Other times, people would fail to tell me I was working with a diesel, and it would be a prechamber diesel. I would turn the key, wait 20 seconds, and think "Time for new spark plugs." Then suddenly I would hear the diesel sound, and be annoyed that I wasn't informed.