Cherry Eye

This morning Banjo had a red eye in the corner by his nose so I freaked out and thought it might be cherry eye. I asked my husband to call the vet and take him in and then I left for work. A few hours later my husband informs me his eye looks fine. I only saw him in the morning so it's possible he had a red eye from just waking up and I freaked out. Does anyone know if cherry eye slowly comes in or if it just pops up overnight? Looking at pictures of cherry eye on the internet the spot where his eye was red is correct but he didn't have any sort of build up on top of the eye. I can't rush him to the vet for every panic I have but I also don't want to overlook something that should require attention.