Looks like you got some DX conditions and another system so happened to be on the same control channel as your local control channel at the same time you caught that. This is E-Skip season.
E-Skip or Sporadic E is the results of 'clouds' in the E-Layer in the atmosphere. Signals from afar can reflect off these clouds and reach you antenna. It also could be tropospheric ducting. Tropospheric ducting is when you get overlapping layer temperature inversion in the troposphere. VHF and UHF will ride along that and go further. Any signal afar during one of these conditions may briefly overcome the local system's control channel then DSD+ will block the interfering control channel data because system data doesn't match.