Formatting a date object to display a human readable date

<%= time_ago_in_words @user.created_at %>

result: 9 hours ago

Date.to_s is not the same as Time.to_s. Your postdate is a Date, so therefore you might want to look at strftime instead:

postdate.strftime("%B %d, %Y")

Or even look to add your own custom date format to your Rails app:
Need small help in converting date format in ruby

The to_formatted_s function already has some common human readable formats for DateTime objects in Rails.

datetime.to_formatted_s(:db)            # => "2007-12-04 00:00:00"
datetime.to_formatted_s(:short)         # => "04 Dec 00:00"
datetime.to_formatted_s(:long)          # => "December 04, 2007 00:00"
datetime.to_formatted_s(:long_ordinal)  # => "December 4th, 2007 00:00"
datetime.to_formatted_s(:rfc822)        # => "Tue, 04 Dec 2007 00:00:00 +0000"
datetime.to_formatted_s(:iso8601)       # => "2007-12-04T00:00:00+00:00"