Yeah on the aerola or whatever it's called.. I have them, I think most people do; when the nip goes hard they stand out like when you have goose bumps.
We are thousands of miles apart and we share the same nipple bumps, cool!
ha ha - nothing to be worried about just keep a lookout for bumps/itchy/puffy. Also take a picture side on view of your nips.. I been on sust and I THINK my nips are puffy but I think it's all psychological - just being paranoid - I wish I had taken before pics!