Our son went through a situation similar to what you are describing with your daughter and we asked the doctor about it. He encouraged us to not call it out as it would make him self-conscious and aware that he was doing it.
The doc's reason for our son doing this was that his mouth wasn't quite able to catch up with his brain and as he learned new words and ways of describing his experiences, he couldn't get it out fast enough to let us know.
This has passed for us and as you described, each time his increased vocabulary and comprehension blew us away. It was like he had absorbed and learned overnight - things we had no clue a kid his age would be able to even notice let alone understand and describe.
Give it some time - if in a month or so from now it hasn't gotten better, talk to her doctor.