Like Tel'kella said, those could be milk ducts. They could also be hair follicles, or pimples, or goosebumps.
Generally, if you'ver got a bump on your areola, and it's not red, oozing, or hurting you in any way, it's probably fine.
Moreover, your milk ducts and hair follicles are supposed to be there.
If you have any pain or irritation, see a doc about it, but you sound like you're just fine from what you told us. ;]
"Ooh, I'll settle down with some old story/About a boy who's just like me/Thought there was love in everything and everyone, you're so naive!"-Belle and Sebastian, "Get Me Away From Here I'm Dying"