Accessing WordPress user meta array values

Here is what I am using to retrieve some custom user meta in WordPress:

$user_id = get_current_user_id();
$key = 'submit_data_' . $cat;
$single = true;
$viewed = get_user_meta( $user_id, $key, $single );

And var_dump($viewed); returns this:

array(2) { 
["catalog_number"]=> string(6) "VIZ025" 
["sub_date"]=> string(19) "2015-09-29 06:40:18" 
}

When I try to access the values using $viewed["catalog_number"] I get an illegal offset warning which I understand but then using something like $viewed[0] returns nothing.

How do I access the values e.g. "VIZ025" and the date string?

I need to use the values in some conditionals like this:

<?php if($viewed["catalog_number"] == $cat) { 
 // stuff here
} ?>

Updated

var_dump($viewed, $viewed['catalog_number']); returns this:

 array(2) { ["catalog_number"]=> string(6) "VIZ025"
["sub_date"]=> string(19) "2015-09-29 06:40:18" } string(6) "VIZ025"

The string(6) looks like it is part of the value which is why I'm getting the warnings. So I need to grab just what is in quotes.

via Chebli Mohamed