Jack-
I've had an A320 return to departure point because of 'control issues'. 'Are ops normal'? 'Affirm' was the answer. Do you think a phase wasn't declared? If ops are normal why are you returning to destination?
There may have been some unserviceablity that is not a not worthy of a PAN (i.e. no priority assistance needed) eg a Prim fault on an airbus, which is unable to be reset. The company may wish the aircraft to be returned to the departure field as maintenance at an outstation may not be available, or, the fault means that with degraded spoiler operation perhaps landing distance available at the destination is not suitable and it is not feasible to continue to destination. There are a lot of variables at play.