Have there been any natural disasters in your area recently? (Not necessarily just in your neighborhood, but in your county?) Whenever we have tornadoes or hailstorms, the roofing companies come out in force. There are a handful which are local, of course, but fly-by-night companies show up and do door-to-door sales as well. Some of them may even be good companies, but we decided to go with one who keeps an office in town! That way if there's a problem, we know where to find them . . .
(Although I will say, advice to people who buy a house in my area is "It doesn't matter how old the roof is." Because it's true - we get enough hail and tornado damage that most homes will re-roof at least once every ten years anyway. On the other hand, it's really important to have an insurance deductible you can actually afford to pay!)