I'm skeptical of the parking brake indication on the FDR.
Obviously, something prevented the wheels from turning, but the parking brake isn't a required parameter so its recording isn't required to be subjected to any kind of periodic functional check. And, well, if the parking brake is really being set as often as I've seen weird indications, Airbii would be the undisputed 'Taxiway A' winner on a daily basis.
And, I've heard of some kind of "Residual Brake Pressure" that results from a system test when the gear is extended (although probably not enough to lock the wheels).