They are her days to take as she wishes. My husband's doctor just took a week off to travel out of the country. Not convenient when we're trying to coordinate treatment at the hospital, but I don't begrudge him his vacation time with his family either. Health professionals have just as much right to time off as any other profession. One of the benefits of acquiring years with many companies is the additional vacation time you can accrue. And in some companies, you use it or lose it.

Whatever the case, you can certainly bring this up to her, so that she might be able to give you more notice, but she is not really obligated to do so.