Nothing like a little Summer tropo to enhance reception! I suspect that you will not find these channels so easily in winter... 40 miles (or so) of the path is across water, so that helps as well! Good catch!
Fox 2 actually transmits on ch 7 so the old High band VHF problem rears its ugly head again.
The CBS channel transmits on ch 44 with decent power (but about 1/2 that of some of the Detroit stations)... perhaps another scan or two would have found it.
jr
Detroit FCC page:
http://transition.fcc.gov/fcc-bin/tv...&slon2=&size=9