xmlrpc.php PHP error

Although it isn’t visible anywhere on my site, my server keeps a log file of all PHP errors. It’s been listing one about 10-20 times/day for a long time as follows:

PHP Warning: Invalid argument supplied for foreach() in /home/firstsho/public_html/xmlrpc.php on line 160

Line 160’s functon (the line with > is actually 160):

function escape(&$array) {
global $wpdb;

> foreach ($array as $k => $v) {
if (is_array($v)) {
$this->escape($array[$k]);
} else if (is_object($v)) {
//skip
} else {
$array[$k] = $wpdb->escape($v);
}
}
}

I have no clue why it would be coming up with this, but just trying to narrow down any errors/warnings so the whole blog works better on a whole. Thanks!