Birth marks?

Can birth marks develop over time? Over the last year or so I've noticed a patch of skin on my pubic mound that's a reddish color. Not super bright. It's actually really light. Almost looks like I have some sort hair dye on my skin that's slowly fading? It doesn't itch or really do anything. It's just a weird splotch. I don't remember having it growing up. I didn't shave that area till about a year or so ago so I'm not sure when it developed bc you can't see it very well through hair.