Flattr Plugin making troube with the_advanced_excerpt

I everybody,

I am using a combination of the_advanced_excerpt, a custom loop and the flattr plugin. Everything worked fine until I updated worpress and also the flattr plugin today. Now I get a warning for all posts which don’t have a flattr button:
Warning: in_array() expects parameter 2 to be array, boolean given in /var/www/wordpress/wp-content/plugins/flattr/flattr5.php on line 314
This refers to the get_option(‘flattr_post_types’), which is correct as posts without flattr button don’t have that option.

However, I really would like a way to avoid that warning, but without having to hack into either of the plugins. The strange thing is, using the_flattr_permalink() works perfectly. So the_advanced_excerpt seems to get the flattr button somewhat differently. I really don’t know and would appreciate your help.

Thanks