Babbling

So Sara has a pretty good vocabulary. It used to be where she would string a word or 2 together and we knew what it was. This weekend she started saying a bunch of new sounds, but not words. Greg thinks that she is just trying to work out new words, and she still has the same old words, but I don't know it is just harder to understand her right now. It is weird. Could it be her trying to work out new words? Should I be concerned? It is so weird.