That's not a bug, that's one of the rewards. Taken from their event post:
1st prize: Tsunade fragment*80
2nd prize: Itachi Uchiha fragment*1
3rd prize: Level 5 Attack Magatama; Level 5 Ninjutsu Magatama
4th prize: Seal Scroll*1; Level 4 Magatama Pack; Summoning Scroll
5th prize: Level 3 Magatama Pack; Level 2 Magatama Pack; Mood Scroll; Low-Level Refine Rune; Medium-Level Refine Rune; Advanced-Level Refine Rune
6th prize: Coins; Dango; Shape Shifting Card; Trumpet; Bond Scroll

The low prizes just kind of *, unfortunately.