Pygmy acting odd...any thoughts?

I currently have 2 Pygmy's. One is 3-1/2 yr and the other is 4-1/2yr.
The younger and smaller one is actually the dominant one and is always throwing her weight around with the other. Especially when it's feeding time. She likes to be in front when I take their feed into the pen. She also pushes the other one around when they're put in at night. Nothing mean, just showing who's boss.
Since this past weekend the younger one is acting odd. As soon as she hears or see's anyone she starts bleating... more than normal.. and much louder. And she continues even after I close the barn until she realizes no one is coming back.
When I opened the barn this morning, she was immediately vocal, and was looking all around like she expected to see something. She is very nervous acting and constantly bleating. I was starting to think that maybe something was around the barn at night and upsetting her, but the other is fine. Then I noticed that her tail is mainly down and she flicks it side to side.
She eats, drinks, poos, and moves about as normal.
My thoughts are that she is not sick, but in heat. However, the loud and constant bleating seems a bit excessive.

We've had Pygmy's for a few years, and have had her since she was a kid, so I'm not exactly new to having them. I just don't recall her ever doing this before.
Anyone have any thoughts?