It was map 2 and enemy phase, Julia had the scimitar equipped and dodged a bandit with an iron axe, then the experience bar went up to exactly 50 %, the stats window popped and she got 1 str, 1 def and 1 luck
Also, when she got 100% she lvled normally . Sadly I don't have a savestate and it hasn't happened again, should i post an image of the stats graphics? I don't know if that will help