unexpected results for diff

[taf2]

macpro.local: (development) 0> s = DateTime.parse("Monday, August 11, 2014")
=> Mon, 11 Aug 2014 00:00:00 +0000
macpro.local: (development) 0> e = DateTime.parse("Thursday, September 11, 2014")
=> Thu, 11 Sep 2014 00:00:00 +0000
macpro.local: (development) 0> Time.diff(e, s)
=> {:year=>0, :month=>1, :week=>0, :day=>1, :hour=>0, :minute=>0, :second=>0, :diff=>"1 month, 1 day and 00:00:00"}

I would have expected :week to be 4 or 5 in the above example. Also :hour and :minute, :day to be populated with larger values...