The NWA CSR told me that due to the 1 hour delay out of PHX, the flight would get in to DTW only at 6.26 a.m. and that since the connecting flight was at 6.30 a.m, I would not be able to make it. Hence he recommended that I re-book for the next day. I do not know how/why the flight landed an hour earlier when it took off an hour later.