I have a theory about that code since it is so prevalent on cars that appear to be operating normally. Starting the car is the biggest load on the battery that it sees, and at that time, there is no alternator output to support the battery either. My theory is that they simply have the voltage threshhold for tripping that code set slightly too high. As the battery ages and the cable connections aren't quite 100%, the dip in voltage that the battery monitoring circuit in the PCM sees at start up is going to be just that much lower than when everything is new and shiny.
Having said that, I would look at the code as a possible advance warning for battery aging, cable damage (serious corrosion), or loose connection issues developing. The only time I got that code on a consistent basis on one of my Concordes, I would reset it, and 9 times out of 10 when I started the car the next day (and it would start fine), that code would appear (and the time on the radio display would reset). I checked thru everything on the power cabling and sure enough, there was some heavy corrosion on the positive battery terminal. Spent a couple hours totally cleaning up and reconditioning that area, and the code/clock reset hasn't occurred since - that was probably 2 years ago.
'98 Concorde LXi - Candy Apple Red | Black chrome ring gages | Black Diamond headlights | Clear turns
'99 Concorde LX - Candy Apple Red | 16" Mille Miglia Cello Wheels | Raybestos PHP cryo-treated rotors | LHS electroluminescent gages