Heavy breathing. Time for the vet?

I've seen my dog breathe like this a couple times already, but never got it on a video before. It usually lasts no more than a few minutes one, or two. In every case it's happened in the evening when we were relaxing same room, same bed. He repositions himself, and then calms down, then he sleeps and is fine. It's worrying me, but I'm not sure what would i say at the vet before i had the chance to film this. He hasn't done any strenuous activity before. This was a few minutes after he drank. It looked like dehydration with the panting, but he didn't want to drink. The room temp was 22.8°C.

I let him out for a potty break, and put him into his crate for the night. He's settled now, falling asleep. It's worrying me though...