I would not get myself worked up over any findings if your doing these tests out of water. If your having issues with 3 feet of red in the water then Id be concerned and get Vex to replace it. They are excellent to deal with. I sent back my Tri-Beam ducer, not because it didnt work properly but because ducer had a big scratch on it from the factory. They had no problems giving me a new one.
Cheers!!