One of the pack of dogs that chases Paladin is a German Shepherd. It has already been established that the time period of this episode (#6.23) was May 1872. The German Shepherd Dog breed was not started until 1899, and it didn't appear in America until later.
In the dialogue Paladin says "last week ...", which occurred May1-3, 1872. He then says that "last May 22, the Amnesty Act for Confederate soldiers was signed". This was also 1872. This puts "one week after May 3, 1872" after May 22, 1872.