No, but I actually experienced about a week of worry/concern when my youngest was about 5 months old. I lost my entire freezer stash (a considerable amount about 300oz!) because the freezer door did not shut all the way one day and we didn't notice it. I literally cried (especially because I was supposed to send 200oz out to a mama that I was private donating to!)
So for about a week, I was really stressing! I work full time, so I obviously pump. I am a good pumper, and almost always have excess, but the thought of not having that freezer stash was very scary to me! At the end of the week I had 30-40oz in the freezer, and I started to relax a little. In the back of my mind, though, I was thinking of plan A, plan B, and plan C!
Plan A: One of my lactating friends either give me some of their expressed milk, or come nurse my baby (three of my friends have nursed him, so that was an easy Plan A).
Plan B: Start solids a little earlier to make the milk last longer.
Plan C: Supplement with something. I wasn't sure what that something was going to be...would I just add a bit of water to the expressed milk to stretch it? Would I add a bit of rice milk? Would I add an ounce of formula?
Now none of these had to be implemented, because I work 15 minutes from home. But there was the chance of a last-minute business trip (hence why I always try to keep 100-200oz in the freezer, enough for me to be gone 3-4 days at least).
So yeah...I understand the worry.
I also understand the "what if some natural disaster like Katrina/tornado/flood/fire/earthquake happened and I got killed, and the stores had no formula or there is no safe water?" I think it could be prudent to put a can of formula and a couple gallons of water in your emergency kit, if you have such a thing. If you survived the disaster, perhaps that can of of formula could save another baby.