How long can genital warts remain dormant?

I guess that's how I wanted to ask this question. I have dated the same woman for 6 years. I believe neither of us have been with anyone else. About a year ago I developed this small blister like thing on my penis. It has not spread or changed at all. I'm not even sure if that's what it is? It doesn't hurt, itch, or anything. Any ideas? Thanks!