If anyone is interested, here is how I solved it.
<% if post.date < Time.now -%>
Due <%=h distance_of_time_in_words(post.date, Time.now) %> ago
<% else -%>
Due in <%= distance_of_time_in_words(post.date, Time.now) %>
<% end -%>
I'll probably make the fonts different, say red for overdue.
Remember to change timezones if you are not living in coordinated universe time (UTC).
#First find your time zone
rake time:zones:local
#My output
* UTC -08:00 *
Pacific Time (US & Canada)
Tijuana
#Copy 'Pacific Time (US & Canada)' and replace line 46 in config/environment.rb
config.time_zone = 'Pacific Time (US & Canada)'
#Be sure to restart your server and you are set to go.