When out of their cages, hamsters will sometimes make loud “sneezing” noises. These are perfectly normal. If she’s sneezing in her cage, it’s likely due to the bedding change. Carefresh is also well known for being a bit... well.. dusty! I don’t believe it’s anything you should worry yourself over. You have the right idea completely- watch for runny nose, lethargy, etc
Best wishes!