error/debug log question - array intersect

Hello... A little bit ago, I added the following custom code to my amember pages:

PHP:

session_start();
$need_one_from = array(3,4); 
if (array_intersect($need_one_from, $_SESSION['_amember_product_ids'])){
   print "User is subscribed to product #3 or product #4";
} else {
   print "User is not subscribed nor to product #3, nor to product #4";
}

It seems to be doing the trick, but I looked into my amember error/debug log, and see a lot of these errors:

PHP:

<b>WARNING:</b> array_intersect() [<a href='function.array-intersect'>function.array-intersect</a>]: Argument #2 is not an array in line 99 of file /home/website/public_html/members/index.php

Now, I do have a few different chunks of code on my page that look like this:

PHP:

<?php
      $need_one_from = array(1);
      if (array_intersect($need_one_from, $_SESSION['_amember_product_ids'])){
         print "<li><a href=\"/members/upgrade-premium.php\">Upgrade to Premium?</a></li>
      <li><a href=\"/members/upgrade-platinum.php\">Upgrade to Platinum?</a></li>";
      }
      ?>


      <?php
      $need_one_from = array(2,4);
      if (array_intersect($need_one_from, $_SESSION['_amember_product_ids'])){
         print "<li style=\"background:#b2ffb9;\"><a class=\"upgrade\" href=\"/members/premium/\">Access Premium Content</a></li>
         <li><a href=\"/members/upgrade-platinum.php\">Upgrade to Platinum?</a></li>";
      }
      ?>

      <?php
      $need_one_from = array(3,5,7);
      if (array_intersect($need_one_from, $_SESSION['_amember_product_ids'])){
         print "<li style=\"background:#b2ffb9;\"><a class=\"upgrade\" href=\"/members/platinum/\">Access Platinum Content</a></li>";
      }
      ?>

Is this a big issue, or can I safely ignore the errors in the log? Thanks.

Thanks a bunch, Alex.