What happened to my pectoral muscle?

I was in the weight room doing unweighted dips and I looked off to the left to check my form in the mirror when I was going down. About halfway through pushing back up, I heard a kind of really quiet popping/sizzling sound and felt a little vibration on the right side of my chest on the edge of that plate of bone in the center of my ribcage. I didn't do any more chest work because I was afraid of hurting it more. Now, it kind of hurts. It doesn't really hurt badly, it's just a dull ache that I get when I breathe out or use my right pec.