You're right in assuming that cats usually gag to eliminate blockage in the airways. It can be a hairball caused by constant grooming, although it can also be a response to overwhelming stimuli. We already have a hard time dealing with overpowering smells. Imagine the impact on an animal whose nose is several times stronger than our own. It probably feels like an attack.
If you're a fan of using essential oils to destress and get better sleep, know that the fragrance the diffuser emits doesn't just dissipate. It lands on your furniture, your things, the floor, and your cat's fur. If the smell is strong enough, your feline might interpret that as a sign to start grooming itself. If you use essential oils daily, it's only a matter of time before your cat's tolerance for the substance wears out.
It's the same with strong-smelling perfumes. A little goes a long way. And when you use too much, it becomes unbearable. That said, gagging can also be a side-effect of another condition. Best have your vet examine the cat to get a proper diagnosis.
Any sign of illness exhibited by your pet should require a visit to your veterinary clinic Clinton, UT for proper medical attention.
