That's good drama... I just have an issue with inevitable questions that come with it. It's not a no deal type of thing it's just... Those questions nag at the back of my head. 
Where was she all this time exactly? 
If she's so powerful her presence anywhere would have been pretty big. Star-Lord certainly didn't ever bring up that OTHER human that's out there wielding cosmic power. Why not? (We know the reason in reality just stating it would make more sense that she would be a known quantity to the various space faring races of the MCU.)
When did she return to Earth? DID she return to Earth? I mean... Did that pager have sub space communication capabilities? 
On the OTHER HAND... 
 I think you could write it that Carol went off somewhere specifically to hone her power and for all we know it ties into her absence. I forget who but another poster recently reminded me about how Eon had a kind of pocket universe where he trained Quasar. Could be that's used to make it that Carol is in tip top fighting shape to take on Thanos as a fully anointed "Protector Of The Universe" in A4?