Not bad at all.

More pressure applied to brake pads (and pads make some contact with the disc at all times). Worse case scenario while driving all day with the emergency brake engaged is prematurely worn rear pads and (remotely possible), warp rotors due to excessive heat.

In your case...negligible to no damage...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car