How to use addFieldToFilter on a custom collection

I was wondering if it's possible to filter a custom collection in Magento 1.7.2. My current code looks like this:

$collection = $model->getCollection()
   ->addFieldToFilter('gc_id',array('gt' => 0))
   ->addFieldToFilter('expiration_date', array('lteq' => Mage::getModel('core/date')->gmtDate()));

I can print the query it generates and if I run it in MySQL I do get the right table rows. However, the collection that gets returned has no items in it. The collection without the filters also returns all the right items, so there are no issues with collection implementation. The collection class inherits from Mage_Core_Model_Resource_Db_Collection_Abstract

Query:

SELECT `main_table`.* FROM `st_freegiftcard` AS `main_table` WHERE (gc_id > 0) AND (expiration_date <= '2013-11-15 23:59:20')

Current ugly workaround:

  foreach($collection as $free_gc){
        if($free_gc->getGcId() > 0 
             && $free_gc->getExpirationDate() <= Mage::getModel('core/date')->gmtDate()){
           ...
        }
   }

I may have screwed up by relying on the xDebug too heavily. Apparently the collection is being filtered by the addFieldToFilter() method, the reason why I was not getting any items to show up was because of Magento's lazy loading. I just had to use the $collection and it would query the items only at that point.