I believe you but, man, that seem small to be seeing noticable differances between males and females. A 3 1/2"er laying eggs? A 3"er with a noticable hump on its head? I have owned many green terrors although I'll admit the last large pair I had was about 10 years ago. I couldn't sex them untill they were 6' or more and even then I was not 100% positive. I had two pair up at about 8"-10" and spawn pretty regularly. They were 2-3 years old by then.
I recently got 6 of them about 2-3 inches long, I can't tell you what sex they are. I can't even tell you for sure what specie they are. (rivulatis I am hoping) One bullies the rest of them by flairing it's gills and chasing the others. It might be a male, might be an agressive female, I don't know, too small to tell.
I'm not really sure what to say about this, at this size they should not be mature enough to be spawing. I guess they could be stunted. I've seen lots of fish displaying adult colors when that are really small and should not be. I think this is caused by mass production of fish, inbreeding/crossbreeding & not being selective about what spawns together. Alot of undesirable traits are being bred into these mass produced fish. The quality of many fresh water fish have really declined in the last 15 years or so, especially with cichlids.
I am interested to hear other peoples experiances or opinions about this.