It's normal for a severely negelected cooling system, IMO. How long have you had the car, when was the last time you flushed and changed the coolant, and what kind of coolant mix are you using? Try looking into your radiator and see what the tubes look like. I wouldn't be too worried for now. Just do a good flush, change your fluid, check your hoses, and go from there. In the long term, you may want to back flush the system, change your hoses, radiator, etc just to avoid cooling problems in the future. Of course if you have cooling problems, now would be a good time to do everything.