Mh. Might be not a bug. Might be a feature.

The 109 was reputed for being able to fly at slow speed so it may as well take up early although it might be less controllable at these speeds. So basically you, by leaving the plane tail heavy, just increased your AoA earlier generating hence more lift hence taking off earlier.

BTW most pilots will initiate take off more actively by pulling slightly on the stick instead of letting her take off.