Is my door warped?

Moved into a new house that's about 10 years old mid-summer this year. So far the house has been great. The issue is with the back door. Let me explain a bit about the door first: * The door appears to be solid wood. It's very heavy. * I think it's 8ft tall and held up by 4 hinges * It has a large and long vertical glass window in the middle of it