If you have to get out of the saddle on your lowest gear to get up some of the hills around you, I would suggest getting more low-end gearing. I like to figure out how many gear inches I need to get up the nastiest climbs In my area, then have one more gear on the low end below that, for those days when I'm semi-bonking into a headwind up a mountain.
Also, the fact that your clipless pedal "fell out from under" your feet sounds bad. If you were tired and your form got sloppy, you may want to think about a lower gear and focusing on your form. If you were just riding normally and your cleat disengaged or your pedal failed, you may want to pay attention to your cleat/pedal setup. You might need to tighten something to keep your cleat from disengaging so easily.
Last edited by Kind of Blued; 05-02-11 at 11:25 PM.