This is in reference to a problem being discussed in issue MONGOID-2567 where fbernier stated that when setting a Time field to a time that is produced using #end_of_month the result upon later examination is rounded up to the next month. The example given was:

MyModel.my_date = Time.now.end_of_month
=> 2012-11-30 23:59:59 -0500

MyModel.my_date
=> Sat, 01 Dec 2012 00:00:00 EST -05:00