Promoting the care and welfare of rats as pets

Hi,

Our rat Flip, who lives on his own now these days (a situation he's very happy with) has started making squeaking noises in his sleep and I'm worried it's an early sign of respiratory infection. He's a relatively old boy, around 3.5 years, but he seems fine - eating and playing happily and with no breathing sounds while he's awake.

I was wondering if anyone else has come across this and what people's feelings are on whether I should get him checked by a vet soon.

Video here: https://youtu.be/_38BXuPuH78 (you'll need to crank the volume a bit!)

Thanks!

Jerome