Asking a premium, not at all fair. She's renting a space regardless of usage, so long as she respects the space and your neighbors. If it was someone conducting a business meeting or a family dinner or on their honeymoon, would you charge extra? If yes to that, then sure, charge her more. She will likely look elsewhere for someone who isn't charging more.
It would be appropriate if she expected extra cleaning or something that is above and beyond typical air bnb service, but otherwise it is unreasonable to charge extra. Hotels don't charge extra and they definitely know what's going on. In my experience with airbnb I was actually charged less because my first time around I did the cleaning and they approved of it, so afterward when I came back again they waived the cleaning fees as my cleaning was just as good as the maids. They knew what I was doing. I was charged extra at places where I asked to adjust the checkin/checkout times, but they would likely do that to anyone as it inconveniences the owner of the unit.
If anything, if she likes the place and you like her she will be back again and again.