Puppy breathing and clear snot

Question
I have a 6 month old, male, neutered, up-to-date on shots and vet care, mixed breed puppy. He has received all his puppy shots and is on heartworm prevention and flea medication. While I am pretty sure the questions I have for you are nothing, I am curious to ask them anyways. Sometimes I let my pup sleep in my bed when he is behaving and then once he is calmed and resting I move him to his crate and he seems to sleep very well with this routine. He usually sleeps under the comforter and I have not noticed anything odd before. Tonight he was sleeping under the comforter and I noticed he was breathing very fast, faster than normal. I looked at him and woke him and he seemed just fine and very comfortable. I woke him up and made him wake up a little, as I was concerned about his breathing, and he was very normal in everything else. When he was awake he was breathing just fine, as in normal. I moved him into his crate and he seems to be breathing normal in his crate while sleeping. In other words, it seems like he breathed very fast only when he was sleeping under the comforter. This is not a sign of something wrong is it? Considering he breaths normal while awake and sleeping in his crate and everywhere else, was it likely the comforter which caused his fast breathing? I always make sure he has access to fresh air as I know the oxygen would be less under the comforter and previously I have never noticed anything and he has been sleeping like this for a few months now. Is this a sign of something wrong or probably just normal due to the comforter, why hasnt he done this before under the same circumstances? Also, I have noticed over the past two days or so he has had a little clear nasal drainage. When he was 8 weeks old he had this too but it went away. He only seems to have the drainage when resting or sleeping, is this normal? It is clear now which I believe means its nor a concern now but when is nasal drainage something to see a vet about? Can pups get colds and could that be why he is producing the clear drainage? Any other ideas about the nose? Other than the isolated rapid breathing and clear nasal drainage he is very normal. Eats great, drinks great, bowel movements are normal, plays all the time, loves to take walks, always up for running around, and seems great but I just want to make sure I seek vet care if he has the beginnings of a problem rather than wait until it is advanced. I am likely making a big deal out of nothing but I would appreciate your expertise to answer my questions. Thanks so much, its great to have something to ask about these simple questions. Just let me know if you think the breathing could be a concern or is likely normal considering the comforter and if the clear drainage is a concern. Also, please let me know when nasal discharge is a concern and when breathing is a concern?

Answer
Most likely he is getting too hot. Since he cannot pant in his sleep his breathing rate increases to blow off the heat.
I am guessing this is a little dog. I would not be training a big dog to sleep under the covers at all.

As far as the drainage goes, he is just getting a runny nose when he sleeps it sounds like. Some dogs get a dry nose, some have a runny one at times. If it is clear and minor, I wouldn't be concerned. If it is copious then I would at least call the vet and ask them.

But the breathing issue sounds like a heat buildup problem. Either keep him on top of the covers or in his crate. They also breathe faster when they are dreaming and puppies seem to dream a lot.