If it were a manufacturer defect, I'd return/warranty it for a new one.

If it were old enough the glue gave up or it was finally damaged enough for the plastic to come off, I'd probably determine it was time to buy a new one.

My helmet is three years old, I doubt its impact protection has been affected at all, but quite frankly after three years of riding it is ready for replacing. The straps and padding is getting quite sweat stained, the shell is still on the helmet, but cracked and chipped around the edges.

Which is a silly argument, because my head is worth far more than $200, but I'd be hard pressed to find a non-special application helmet in excess of that value.