Will the service center (Canon/Nikon) help you clean the interior of your lens if it is will under warranty? Do do you have to pay for the service?
Definitely not worth risking the warranty cleaning it myself.
Warranty is not a free cleaning service, it is to repair and replace faults due to manufacturing and in material. Since neither Canon nor Nikon claims that the lenses are dust proof they won't accept any claim for free cleaning.