Rspec tests failing if run all together

I've 2 _spec files: the first containing unit test, the other one some integration tests.

While running them by specifying file name they are alle green, while running them as "rspec" 3 of them are failing.

I'm using database_cleaner gem to clean test db around each test.

config.use_transactional_fixtures = false

  config.before(:suite) do
    DatabaseCleaner.strategy = :transaction
    DatabaseCleaner.clean_with(:truncation)
  end

  config.before(:each) do
    DatabaseCleaner.start
  end

  config.after(:each) do
    DatabaseCleaner.clean
  end

I'm using "let" to instantiate objects and FactoryGirl to create sample objects.

Has anyone experienced something like this before?