Depends on the cat. I would ask my vet to make sure it's not an infection, just to be sure. But some cats always get gunk. Mine had feline herpes to start with, and was so sick when he was found by Chicago Animal Care and Control that they think his sinuses were irreversibly damaged, so he almost always had drippy eyes.
Many cats get dried up gunk in the corner of their eyes when they sleep. Kind of like us Humans finding crusty gunk in the corner of our eyes after sleeping. It's normal. Occasionally the eye gunk is moist and stringy but that's generally normal. Just clean the gunk away with a damp tissue. If the eye otherwise looks fine, you don't need to worry.
Link tends to get eye boogers and is a huge protestor if me wiping them away. But yeah, normal as long as the eye look otherwise fine and it is just a little bit. If its running down their face or constant you'd want to consult with a vet.