It's been a very warm and early spring here in Michigan.
A few years ago we did "no mow May." The grass is taller now than it was at the end of May then. A quick Google says average L/H for Detroit is 40/50 in April. It's been significantly warmer than that with many days in the 60s and 70s.
Are you from Michigan or did you move here recently? Or perhaps you live further North?