va58, you jogged my memory.
I am a native Californian and was in my mid-teens and mid-20s during the 70s decade. I recall that around 1974 it became popular to detail the wheel wells of our cars. Not only did guys and gals paint the the wells, but they would add mudflaps from a large selection of sizes, types, and materials (metal vs. plastic). I recall some people removing their lip mouldings because they didn't look right with the flaps or because they interfered with the installation. Some cars needed to have holes drilled into the lip if they didn't have the moulding. I know of a few guys who tried to use the fender bolt as an attachment point instead of drilling and their flaps would be cockeyed. Wheel well lights were sometimes installed. I don't know if it was just a California thing or if it was a thing that was being done across the country.
It might be that a previous owner of the car began to do something like that and decided that it wasn't a good idea after starting on one side.