foreach warning when importing contacts in 4.1b3

Environment: Drupal 6 & CiviCRM 4.1b3

When Importing Contacts via CSV I get the following warning once for every imported row:

warning: Invalid argument supplied for foreach() in /XXXXXXXXXX/sites/all/modules/civicrm/CRM/Import/Parser/Contact.php on line 1903

I'm matching up Lastname, Firstname, Address, City, State, Postal Code, Email for each entry. I'm not sure what other info would be helpful to debug, so please just ask and I'll see if I can provide it.