If your son was 18 years of age or older your insurance covers both you and him when he is driving your car with your permission.
If he is between 16 and 18 with a valid license and you only own and insure one car there should be no issue either.
the only time the insurance can really fight it is if you own 2 vehicles and both are listed as you being the primary driver when there is a second licensed driver in the household.