Hi Troy,
I I just want to say - you should never feel obligated to contribute to a project. And, you should never feel guilty when you don't have the time. It's a volunteer project, and for the project to be healthy the volunteers should feel that they won't be disliked, or accused of not being active, or scolded if they find themselves unable to participate.
Everyone who contributes, please feel confident in knowing that, yes, Joomla does need and rely on you, but no, you will not be scorned for not being available.
The is some great content about volunteering you may want to check out (when you have time!):
5 Stages of Open Source Volunteering
(An oldie but goodie): Open Source Projects and Poisonous People