After naming one of my sheep "jeb_" (to get all the rainbow changing colors and stuff) I went far away to do stuff, and when I came back the sheep named "jeb_" was no longer named jeb_ and it turned into the boring old white sheep. So I got another name tag and renamed the sheep jeb_ and went far away again to do more stuff. When I came back, same thing happened. I never punched or sheared or did anything to the sheep besides naming it and attracting it with wheat.

btw, above I listed the device "iPhone 6" but I was actually playing on the iPhone SE (there was no selective option for the iPhone SE).