No, a graphics glitch. To see if you can resolve this, run the OFP preferences program and make sure that DISPLAY DEVICE is not set to a HW T&L setting. If you're running OFP 1.30 or above, start OFP and select OPTIONS from the main menu. Under VIDEO OPTIONS, make sure that W-BUFFER is disabled. Save and test.
If that worked, try enabling either W-BUFFER or HW T&L (but not both) to determine which one caused the distorted graphics. If both settings individually cause the problem to reoccur, you have to keep both disabled.
In any case, maybe now is a good time to check if your graphics adapter's manufacturer has released a new version of your adapter's drivers.