SEA-DTW delayed 20 minutes initially. Freeway traffic was brutal so I was cutting it close. Got to the gate after boarding was supposed to start and there we stood. Got on the plane, pulled back from the gate to de-ice and something happened with the APU. Back to the gate, wait for the mechanical crew, verify all is well (no APU though) and finally depart 2:15 after schedule. Not horrible considering some of what I am reading. Definitely a challenging travel day.