PHP Warning on Appearance->Customize page

Hello,

Love the Hemingway theme, thanks!

Everything works fine but I spotted a PHP warning message flashed right before the Customize page finished loading.

Here are the HTML source (the message is covered by the actual customize page immediately on loaded).

<b>Warning</b>:  Invalid argument supplied for foreach() in <b>/home/(username)/www/www/wp-admin/custom-header.php</b> on line <b>1248</b><br />
<br />
<b>Warning</b>:  array_merge() [<a href='function.array-merge'>function.array-merge</a>]: Argument #2 is not an array in <b>/home/(username)/www/www/wp-admin/custom-header.php</b> on line <b>1268</b><br />
<br />
<b>Warning</b>:  Invalid argument supplied for foreach() in <b>/home/(username)/www/www/wp-admin/custom-header.php</b> on line <b>1248</b><br />
<br />
<b>Warning</b>:  array_merge() [<a href='function.array-merge'>function.array-merge</a>]: Argument #2 is not an array in <b>/home/(username)/www/www/wp-admin/custom-header.php</b> on line <b>1268</b><br />

It looks like something related to the header image but I could use that function without any error. I am using WordPress 3.9 and tried to reinstall the theme already. It persists.

Do you have any idea on this? Any help would be appreciated.

Thank you in advance.