Dogs DO smell with their tongues, and this may have started that way and now become a habit. Most likely not bloat at there are many other more obvious and fast developing symptoms that occur with bloat.
as for sleeping under the covers - I would not be too concerned with that. We put our dogs in their beds at night and then cover them all up with their own blanket and they love it. If dogs get cold at night they are going to find the warmest spot.
How long has been this been going on? Get your dog to a vet. Have it checked for bloat. Licking at the air, seeking a hiding place, only two symptoms, but there are many more symptoms other than those two.
Also, licking at the air, dogs have a more presice smell, having very sensitive receptors on their tongues..
And in some cases, licking at the air could be from teeth problems.
By all means though, get your dog to a vet so a medical check can be done to find out the cause.
"Air licking" can also be a sign of a partial seizure. Your dog needs to see a vet.
Thanks for the comments! I didn't realize that dogs could smell with their tongues! I learn something new everyday! Tuxedo is very healthy. He goes to the vet two times a year. He just had his last check-up the end of March and everything looks great! I get his teeth cleaned every March. I never thought his tounge-licking and sleeping under the covers was serious, but I was curious about the why behind it and now I know. I do not groom Tux like a regular poodle. We get his hair cut short so I am sure he is cold a lot. On cold days, we will find him sitting at whatever window the sun is shining through.