A lack of grooming behavior is always a concern because it's a natural instinct to keep themselves clean.
I would want to go ahead and see the vet with him for an exam and some bloodwork to find out if anything strange is going on.
If this is anxiety based, you might want to try a homeopathic anxiety medication called homeopet (www.homeopet.com). You can get it at most petstores.
Let me know if you still have questions.