Warning after upgrading to v2.5.1

Hello,
After upgrading to version 2.5.1 (two days ago) I found this error in my error_log again and again:

[05-Dec-2012 08:32:30] PHP Warning: in_array() [<a href='function.in-array'>function.in-array</a>]: Wrong datatype for second argument in /home/mydb/public_html/mysite/wp-content/plugins/antispam-bee/antispam_bee.php on line 1768

On the antispam_bee .php file we find the last line on this code:

private static function _handle_spam_request($comment, $reason, $is_ping = false)
	{
		/* Optionen */
		$options = self::get_options();

		/* Einstellungen */
		$spam_remove = !$options['flag_spam'];
		$spam_notice = !$options['no_notice'];

		/* Filter-Einstellungen */
		$ignore_filter = $options['ignore_filter'];
		$ignore_type = $options['ignore_type'];
		$ignore_reason = in_array($reason, $options['ignore_reasons']);

The plugin seems to still work fine -caught 395 two days ago, 420 yesterday and 255 so far css-hacks today.!!!

Does anyone else have this warning as well?

I also have W3 Total Cache activated. Could there be a conflict?

PS: By the way. Any specific reason why the whole plugin turned into German? Just wondering…
https://www.ads-software.com/extend/plugins/antispam-bee/