I thought I lost my baby..

Yes, I have a small program, I've been spending months to feed it little and little everyday. And last night before going to bed, I saved it into my USB drive as usual and all of a sudden I saw an error message while the file transferring dialog was still being shown that "An error has occurred and file can not be written to disk". I pressed OK button and discovered that the directory I tried to moved to USB still existed in the local hard drive, only some folders in there disappeared. Like a nightmare, I looked into the USB drive to see no folder was created either. "No, the world ends, no way I can created everything from scratch, I don't have the nerve to do all it again", I thought to myself. And at that disappointed moment, the light was out [In my area this is quite often happened lately].
Some 15 minutes or so, when the power was back on. I booted my computer and discovered that all my files were there in the USB location as once specified for file transfer. That's magical and fabulous to me; I promise myself to stick with my baby, just won't ever give up.

Anyone could explain me something ?