I am on my third time of having my door locks go out. I just keep fuses readily available in my glove box...just like when I was 16 driving my old beater...HA!
There is a SIB regarding this:
http://www.bmwtis.com/tsb/bulletins/...p/B511907g.htm
There is an issue and it should be resolved the proper way so just make sure if it happens again you can bring this to their attention. I have also found that once this starts happening it typically becomes an issue with the car which I suspect is the reason it calls for a 20A Fuse vs. 15A in the SIB.