I'm not sure. Would he be itching alot if he had mites?Why does the fur look wet?
Back of the neck is a usual spot for mites, there could be other reasons though if the skin looks healthy, like a rare, wiered molt pattern. A fungal infection might be another reason. If he isn't in a molt and/or the skin is irritated, flaky, crusted or wet - I would see a vet.
He doesn't itch at all or seem uncomfortable. He seems perfectly happy and that . His fur isn't wet I just checked.It would be hard to notice because he caan't reach this spot. But yes, at some point a mite infestation does get itchy and hurts.
My vet didn't find mites at the first visit, I went there again when the skin started to ooze fluid, and that sure was uncomfortable then, it was mites. Hence my question about the wet looking fur. Simple treatment with stronghold drops around the area twice, 3 weeks apart solved the problem.
But as i said, there can be other reasons for a bald sopt.