Found a hard lump on the bone of my sternum- concerned?

I’m a 22 year old female and today I noticed for the first time a small lump (about the size of a pea) near the centre of my chest. It feels like bone and is on my sternum. It’s only on one side and I’m certain it wasn’t there before (at least not since a few weeks ago). 

I’ve never had any serious physical health conditions but cancer does run strongly in my family.

Should I be worried and get it checked out, or is it likely just a weird bit of bone growth?