The following script works fine for me:

<?php
$array = array(
	array('foo','bar'),
	array('test','hello'),
);

$i = 0;
foreach ($array[$i] as $key => $val) {
	echo $key . $val;
}
?>

You'll have to provide a complete script that gives unexpected/incorrect 
warnings.

Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

The syntax you provided works just fine and doesn't emit a warning if $array[$i] is an array... for example:

$array[2] = range(5, 10); 
$i = 2; 
foreach($array[$i] as $key => $val) echo $key . '->' . $val . PHP_EOL;