Yesterday I noticed there is some separation between my Chubby 2's knot and the handle. It would seem like the knot might be coming undone. I lightly pulled on the knot, and it did not give. Is this a case of it starting to come undone, or is it normal on a chubby? I checked my other brushes and they don't have this gap between the knot and the handle. Any advice would be greatly appreciated.