Not likely. He probably saw a white tail that was a little dark. Blacktail are strictly a Pacific Northwest deer.
Whitetails are Odocoileus virginianus
http://www.mnh2.si.edu/education/mna/image_info.cfm?species_id=231
It is easier to tell them apart by the antlers than the tail color. Blacktail and muleys have a main antler beam that goes up then branches. Whitetails have a main antler beam that goes forward and the tines go up.
Some animal lists don't even include the Blacktail. They say that they are a subspecies of Mule Deer.
Odocoileus hemionus
http://www.mnh2.si.edu/education/mna/image_info.cfm?species_id=229
This link tells you more than you will ever need to know about blackies.
http://www.blacktailcountry.com/html/blkpage.htm
In the field, I can't actually tell the difference between mule deer and blacktails, but I think the horns hanging in my garage are blacktail.
Keep your muzzle in a safe direction!
Leigh M
http://www.NWSafe.org