It's sometimes hard to see just exactly what is being observed by a description with words. As aluz said above, the "vibration" could very well be one of those things. I don't want to scare you, as I said it's hard without seeing a video of her doing it, but my late budgie Pix had some serious genetic problems which had been determined by 2 avian vets. It affected several body systems. He'd sit and vibrate his wings close to his body extremely fast, and without additional body language. This was probably a neurological issue. If you have any question about whether it's normal 'behavior based' wing vibrating or not, it's always best to take a video (I know it isn't easy when it's not being done constantly), or even better, take her to an avian vet. Good luck!
Edit: another thing it might be.. Birds of the parrot family including budgies, will lean over with a flat back and quickly move their wings as they hold them away from the body when they are interested in coming over to you. All the more when they aren't flighted and can't reach you.
Last edited by RavensGryf; 10-24-2016 at 12:46 PM.