Not sure of you mean the really loud squawk (compared to their other sounds) or just a 'voice leveled' squawk?
Pickle squawks at me in the not-so-loud way a lot.

I think hes just being bossy. He squawks when its time to get up, he squawks into his bowl after i give him food, if he wants me to carry him somewhere, if he hears my car, if we are playing and he needs to go back to the cage to do his business, if i start making MYSELF food etc... because i do everything for him and he knows there's no point asking anyone else in my family for anything.
He cooes at everyone else cutely and nicely ALL the time and i only get this when he thinks I've been good. XD *siiigh*
Then again we live in a big house and even the humans here shout across rooms to each other, so hes just doing the norm. In our house it is nothing that can be changed or worried about unless i change the whole dynamic of the family and since i haven't tried, i don't really have training tips for you.
From what you said i wouldn't worry about boredom either, has she always squawked? Or is this a new change in her behaviour? I don't really know, but i would be more inclined to worry if it is a change that you cant think of any reason for, not if shes just always been like that...
