Coughing kitten

My 14 week old kitten Jessie seems to have a little cough that has been going on since we got her 4 weeks ago. It only seems to happen in the evening when she's laying on you and purring but it's not constant and soon stops. She also has an extremely quiet meow and sometimes she looks like she's meowing at you but no sound comes out.

She had a vet check a couple of weeks ago when she fell out of a window (no injuries thank god!) and the vet deemed her perfectly healthy. Any ideas what it could be?

The quiet meow is nothing to be concerned about as many kitties are not loud at all, unlike ALL of mine who have very healthy meows.  LOL  Many feral moms teach their kitties to not purr or meow so as to keep predators at bay.

The cough is very concerning.  I'm wondering if she's just got a lot of drool from all the purring and petting and she chokes on it a little bit?  Definitely something to keep an eye on.  Do you notice any nasal or eye discharge or stuffy nose?

The other kitten Luna has an extremely healthy meow and is very vocal!

It could be I guess. She definitely doesn't have any nasal or eye discharge. I have noticed though that when she's sleeping she kind of whistles and squeaks. Not the kind of noise they make when they're dreaming. But almost as if she isn't getting enough breath in. She seems perfectly healthy and it doesn't seem to affect her at all though and the vet checked her breathing and lungs and they were fine. It's something I'll be keeping an eye on though!

She sounds like a cutie!  Post pics of her in the picture forum when you can.