Yes, definitely talk to the insurance company, or have your mother speak to them. There are usually ways to get coverage for any vehicle you drive, a mobil insurance so to speak, even when you don't have a vehicle of your own.
Making sure you have coverage in this manner is always a smart thing to do, especially since some people's insurance policies might exclude other drivers or drivers not in their household. You definitely do not want to think all is copacetic and get in an accident and find our a friend's policy did not provide coverage for guest drivers.
We have a policy like that, it covers only my husband as a driver and no one else. So if we lend our vehicle to a friend, they must have some form of coverage for it, otherwise there isn't any. So far, only one of our friends has this on his policy, so he is the only one who ever gets to borrow our Grand Caravan.