Gagging like a person would do? Like a dog after eating grass? Noises? Movement? Is anything visibly coming up?
The only normal thing I can think of that this could be would be anointing. If that's not what he's doing then no, it's not normal behavior.
Any change in diet? Any dehydrated foods, seed or nuts? Possibly a small piece of bedding stuck in his throat? How frequently is he doing it?