You are definitely not alone. I have a gorgeous Great Planes Super Stearman that I just finished and have about 15 flights on it in a matter of 3 days and I still feel my knees shaking right after takeoff and right after landing. Like you during the flight I am perfectly comfortable

As you get used to the plane the nervousness subsides but it can be a good thing as it will make you more alert and careful. Look at it this way. You must really like the plane. If you didn't you probably wouldn't be so nervous.