Found a 1% Clean Slate Scroll

Okay today I logged in at CrimsonWood Keep and decided to train a little while with the NightShadows. I was there maybe 20mins and then my friend logged on and I told him I could train with him for a while at harps. I bought a 2x drop card and went to leafre. After a few minutes there I opened my inv and noticed I had a scroll in there. I didn't gacha or do anything with the box event that we had and I don't have the mesos to buy anything . So the only thing I can assume is that my pet looted this from either the NightShadows or the harps. Anyone have an idea where I got this from? o.O