It is normal. Because the 3d glasses are heavy, you will feel dizzy when you wear it to see the movie for a long time because of the pressure on the nose. However, someone may feel the dizzy eyes because of the not comfortable symptom on the rear ears. It is also caused by the heavy weight of the 3d glasses.
Well, as you can see, 3d glasses are simply designed to give us some special visual effects when we are watching a 3d movie in the theatre. Anyway, it depends on different people, some people are ok with 3d glasses, however, some other people will feel dizzy, even throw up when wearing those 3d glasses. Maybe it is just a matter of adjustment, people will be better when they are used to 3d glasses.
It is normal, but it is not only the 3D glasses that make you dizzy. The bad 3D content is source. Making a 3D film is easy, but making it good is not so simple. Some common mistakes in the process of making film can lead to discomfort and dizzy feeling. Besides bad content, the speed also can affect our feeling.