I wouldn’t worry too much about it. YOu probably don’t have to try to limit your neck movement. I mean, unless you really want to. But, keep in mind, it’s your neck, man! it’s going to be moving around when you look up or down or anything.
I just got a tattoo on the back of my neck about a month ago, and it was kind of the same. Its small, but in the middle of the tat, where my neck sort of “creases” when i look up or whatever, it wasn’t healing the same. Just keep lotion on it so it’s not so dry and prone to cracking, but don’t put any lotion on it when you sleep. That’s what I did and it turned out beautifully!