Absolutely, yes. It would be best if you resealed your granite every year. Despite being an incredibly hard and durable stone, it is not impervious to damage. If your granite countertops are not properly sealed, it can lead to stains and bacterial colonization in the countertops. And you certainly don’t want that anywhere near where you prepare and serve your food.
These problems and acidic foods or cleaning agents can damage the stone. If you want your countertops to maintain their beautiful shine for their long lives, you’ll want to seal all granite countertops.