Blue and Golds are AWESOME!!! They are the most laid back branch of the Macaws. I own one with another to join our flock within a month or so.
Birds are so much smarter than people give them credit to being. They are also creatures of habit. If in those situations, you spoke to Sarge consistently with those words and phrases, then he is going to relate them to the action on a daily basis. It is all part of his regular routine. If my blue and gold Cookie, sees me eating something, it is immediately Ummmmmmm! Lacy, the other blue and gold we are adding to our flock says Ummmmmm ... want some? when food is being eaten around "her". Cause in each situation, that phrase was spoken each time food was being eaten and offered to themn they relate it to the process of eating and use it each time the process happens.
You should be able to add another macaw to the flock with no change to the behavior as long as each macaw has their seperate cage/home. If placed in a cage together, then there is a good chance the two macaws will bond together and refuse your friendship anymore. That is why we actually do not suggest mirrors to anyone we sell a bird to (I work in ithe bird dept of an awesome family pet store in Va Bch that is known for their bird and reptile depts) if they want the bird to bond with them. If a mirror is available, it looks at it's reflection as another bird and bonds to it.
Macaws are awesome. I have a tendency to lean towards them and Cockatoo's at the pet store I work at. But I am upfront with people about the high maintenance level with a cockatoo. But I am always drawn to the macaws. There is a Catalina Macaw at the store I would love to own. He is a big bluffer. He makes people think he is a menacing macaw by lunging at fingers but if people were not so afraid of their intimidating beaks, they would realize that Rocky doesn't actually bite you!! LOL Plus he makes alot of grumbling noises that people mistake as aggressive 'scary' noises. Funny thing is that a macaw has aprox 1500 psi of pressure in their beaks compared to the 3000 psi of a cockatoo beak. Bigger beak in a macaw but less pressure!
The short of it all (I know too late!) .... yes, this is normal behavior for a macaw who is active in it's humans lives. The more interaction there is from the humans, the more the birds will understand and mimic.
Smiles!
Kristi