I noticed today that a tattoo on my shoulder feels raised when I run my fingers over it. Is that normal?

This is a small tattoo I've had for just about six years, and I can't remember ever noticing this before. When I touch it, it feels a little bit like the lines are on top of my skin, like scars. I have another tattoo on my back that is behaving normally.

Is this a normal occurrence? I'm mostly just curious about why it's happening.

EDIT: Thanks all!