My Pug has cherry eye!!! HELP?

Well, I don't know if it's really cherry eye because I only see the "red eyelid" once this morning when I woke up. When I took her out to play, it's gone. It's more like an on-and-off thing with my dog. was it really cherry eyes? Should I take her for surgery? Is it really hereditary? Because my vet told me some dogs are more prone to it and the usual cause are irritants. NOT HEREDITARY