Active record bug with heroku and postgres

Gemfile.lock

GEM
  remote: http://rubygems.org/
  specs:
    activemodel (3.1.3)
      activesupport (= 3.1.3)
      builder (~> 3.0.0)
      i18n (~> 0.6)
    activerecord (3.1.3)
      activemodel (= 3.1.3)
      activesupport (= 3.1.3)
      arel (~> 2.2.1)
      tzinfo (~> 0.3.29)
    activesupport (3.1.3)
      multi_json (~> 1.0)
    arel (2.2.1)
    backports (2.3.0)
    builder (3.0.0)
    eventmachine (0.12.10)
    haml (3.1.4)
    i18n (0.6.0)
    json (1.6.4)
    logger (1.2.8)
    mailfactory (1.4.0)
      mime-types (>= 1.13.1)
    mime-types (1.17.2)
    monkey-lib (0.5.4)
      backports
    multi_json (1.0.4)
    pg (0.12.2)
    rack (1.3.6)
    rack-protection (1.2.0)
      rack
    rack-test (0.6.1)
      rack (>= 1.0)
    sinatra (1.3.2)
      rack (~> 1.3, >= 1.3.6)
      rack-protection (~> 1.2)
      tilt (~> 1.3, >= 1.3.3)
    sinatra-advanced-routes (0.5.1)
      monkey-lib (~> 0.5.0)
      sinatra (~> 1.0)
      sinatra-sugar (~> 0.5.0)
    sinatra-contrib (1.3.1)
      backports (>= 2.0)
      eventmachine
      rack-protection
      rack-test
      sinatra (~> 1.3.0)
      tilt (~> 1.3)
    sinatra-reloader (1.0)
      sinatra-contrib
    sinatra-sugar (0.5.1)
      monkey-lib (~> 0.5.0)
      sinatra (~> 1.0)
    sqlite3 (1.3.5)
    tilt (1.3.3)
    tzinfo (0.3.31)

PLATFORMS
  ruby

DEPENDENCIES
  activerecord
  activesupport
  haml
  json
  logger
  mailfactory
  pg
  rack (= 1.3.6)
  sinatra
  sinatra-advanced-routes
  sinatra-reloader
  sinatra-sugar
  sqlite3