Yes, I have found that one as well. It states the following:
The easiest way to fix this issue is disable the 1.2-compatibility layer included in MooTools within the RockSprocket plugin. Because the MooTools within the plugin is 1.4.5.
So, for now, the best bet is contacting the makers of RockSprocket to see if they can fix this issue.
So how do I disable the 1.2 compatibility layer in your mootools plugins?