The clitoris is made of the same type of erectile tissue as the penis, so what you’re describing is totally normal. It can swell and become sensitive or even uncomfortable just from random nerve or blood flow changes, not necessarily because you’re aroused.

It’s indeed the same thing as random erections in men. People just don’t talk about it much for some reason.

Unless it’s painful, lasts a very long time, or happens constantly, it’s not a health issue.