While many people believe this is a possibility, we have never encountered any problem with this. In fact the ST-4 had no external control of the cooling and you simply "pulled the plug" to turn the unit off. We never had one return for a failure of the TE cooler.
The firmware in newer cameras do, however, slowly ramp the TE cooler power down when you use the Shutdown command or when you disable cooling in the Camera Setup command.