[Gameplay] Red Dark Star Thresh: Is this supposed to be a bug?

I was playing around as Thresh in a practice tool using Dark Star Thresh skin. I toggled Refresh Cooldown button and kept on spamming Thresh's Q on a target dummy. When I spammed his Q on a target dummy, Thresh suddenly turned into red instead of purple. At first I thought it was a bug until I realized the frog in Dark Star Thresh's taunt/joke (not so sure) is also red instead of green. Is this a bug?

Photo: http://grabilla.com/0731e-cbd42518-6cac-4d50-9d70-acc21feba08b.html - Normal Dark Star Thresh

http://grabilla.com/0731e-f770392d-728e-4fef-a268-ecf92bf8b24d.html - Red colored Dark Star Thresh after spamming Q to a target dummy with Refresh Cooldown button toggled