Factory calibration values were restored from the bootloader area

What ArduPilot says:

• Loaded N persistent parameters (N errors)

Some boards keep a few parameters in the bootloader's part of the flash, where a full parameter reset or a firmware change does not reach: mostly the factory calibration of the IMUs. At start-up ArduPilot found such a list and used it as the default for that many parameters. A value you have set yourself still wins. An error is counted when the saved list belongs to other accelerometers than the board has now; loading then stops at that point.