iPhone UITableView starts with offset in ios8, possibly due to tableViewFooter

My UITableView is starting with empty space between the top edge and the first section. Image here.

This problem occurs on iPhone but not on iPad. The table view has one section with a section header (a custom view set via tableView viewForHeaderInSection) and a UIActivityIndicator as the tableFooterView. The offset disappears if I remove the tableFooterView, so I guess it is related to that. But, I need a solution that keeps the footer, and I'm curious why it's happening in the first place.

Any thoughts? Thanks!