Does A Small Lump Just Beneath Sternum Indicate Hernia?

I have a small lump just beneath my sternum. It s not painful and I can move it slightly. It s more pronounced when I lean back. I do a lot of powerlifting and am a regular gym goer. I m wondering I its a hernia? Something else? I m scheduling a doctors appointment soon. There is a occasional minor heartburn as well, though not regular. It is in an isolated area and has not increased in size. Any help or suggestions please?