My hen's a roo...I think

[PenelopeFlys]

I have 6 hens ( I thought when I bought them as day old chicks anyways)- 4 barred rocks, 1 RIR, and a light brahma-named Sunny. They are now 3 and half months old. It's been apparent from early on that Sunny was the "alpha hen" of the flock, and then 2 days ago, Sunny started crowing around 7:30 in the morning. She only crowed about a few times and then stopped. My guy and I think now that Sunny is a roo...in hindsight..the chest bumping, the feathers around her neck all ruffled and how the rest all follow her around...Well, last night- we went outside to lock the coop because it was late evening- normal ritual. Instead of them all being in the coup roosting, they were in another part of the backyard (2 on the grill, one on the fence...etc) The only one in the coup was Sunny. So, my question is- Is Sunny going through some sort of chicken/rooster puberty? Is that why all the other girls were not in there with her/him? She seems to be her normal self otherwise...