Cdawson,
There is a 700 gallon saltwater tank in a local japanese restaraunt that is filled to capacity with live rock, corals, and macro algae. It is a reef wonderland. It also contains several triggerfish which display the exact same glass swimming behavior, so don't feel too bad about not having a "complex" enough system. This is the most complex and pristine aquarium I have ever had the pleasure of viewing, and these triggers swim up and down the glass non stop. One of the Angelfish does it too. Maybe this behavior is just a fish quirk, or maybe Childawg and RTR are onto something. Anyway, your condition is not unique.