Has anyone's electric blue legged hermit changed colors?!

Hey guys! I have had a large electric blue legged hermit for about a year now and about a month ago he changed to an almost "rusty" purple color. I know it's him because he's the only large hermit I have, I have 12 small ones and they are all accounted for. Is this possible? I mean, yeah it is cuz it happened lol. But WHY?! lol