That is what was reported in FOX-y lady. Although, in Meet the Quagmires, everyone is 18 in 1984. This could have been an alernate timeline caused by Stewie's (or another entity's) manipulation of the time stream. In Death Lives, Peter as a teen meets Quagmire who is already in the Navy as an ensign, indicating he had been in for awhile. He also has an adult son in Madrid, Spain in Peter's Got Woods, also indicating he may be older than he appears.