It may not be significant, but all the placards in our Arrow are consistent with what's in the POH, which actually says there shall be placards reading thus, and so - as indeed there are.
We had a slight discussion last year when our avionics annual produced a new placard that the GNS430 was not approved for use under IFR. Turned out the CAA document that was needed for it hadn't been applied for. Soon resolved.
So if the placards say DAY VFR ONLY, and you have all the Night/IFR kit, I would ask the maintenance folks why. If they don't give a sensible answer, well, ...