Spayed cat nipple

My almost 3 year old cat was spayed when she was about 10 months, she had already had one litter that I know of(she was adopted) and she has one nipple not sure I should say swollen , but bigger than the other ones who are pretty much flat, it sticks out and I think it has probably always been that way since I've got her, I'm not very sure though, the thing is that it sometimes becomes very pink , once I caught her licking it out I knew she had probably irritated it, but she's now with an onesie due to a tummy injury and she couldn't possibly be licking it that I know and since I'm constantly healing her tummy injury I notice that sometimes it is very pink and sometimes it is normal, no discharge or anything else,but always bigger than the other ones, could this be dangerous? I've got a vet's appointment in less than 2 weeks but still would like to know if anyone knows what this could be? I hope is nothing too serious.

Bumping for you, in hopes that someone has seen this before.  

I would definitely bring this to the Vet's attention during her next visit in 2 weeks.  It might be nothing, but it could be something.  Since you suspect she's had it for quite some time, I doubt waiting another two weeks will hurt. 

Keep us posted.

thank you,  I just wanted to know  if it could be anything else other than a tumor(I'm always thinking about the worst) since I don't know what other things can happen in there, I hope it's nothing or just nothing serious.