Is it normal to want to jump off the sides of the treadmill constantly

I am a young woman who loves fitness. I am currently training to be a fitness instructor. About 4 months ago I was in a strength and conditioning class where I had to do sprints on a treadmill and jump off to the sides when my time was up and go on to do floor work. I would do this repeatedly. I was very nervous about going at such a high speed and was anxious to jump off to the sides. Sometimes I would jump off a few seconds too soon. I was afraid I would fly off. Now months later after being on the treadmill several times and having no problems doing my normal run I have found that I have the urge to jump off to the sides. The other day, I couldn't run but a few minutes and then have to jump off. I kept trying and trying to stay on but I couldn't control the urge and would jump off. After several times I gave up and just quit for the day. I then went and ran on the track. I am very upset this is happening, and I cannot control it. What has happened? Is my brain malfunctioning or what? I am very very upset. This is a part of my daily routine;its what I do.