Wordpress Error (after tons of plugins)

Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 15737 bytes) in /home/XXXXXX/public_html/XXXXXXXX.com/wp-includes/functions.php on line 251

Has anyone ever experienced this? I started getting it after activating my 20'th plugin. All of which are WPMU Dev plugins. What does this imply? I can refresh and get around it but I am concerned...