Hi San Diego-
Browlifting and Botox to the forhead should never result in abnormal mouth or lip motion. The muscles and nerves affected by the browlift and forehead Botox have nothing at all to do with the upper lip. Unlike after rhinoplasty where there can be some temporary alteration of the smile because of swelling, there should be no way that brow swelling after browlift affects your smile. Furthermore, Botox physically can't diffuse from the brow into the upper lip and cause smile "deadening".
Any chance you might have recieved some Botox into your upper lip while you were under anesthesia? Another question I'd want to know is if you are having any other muscle problems such as swallowing difficulty, tongue weakness, eye muscle weakness, double vision etc. If you are having any other such neurologic symptoms, see your primary care provider or a neurologist for an evaluation. If not, and you otherwise are doing fine, I'd just wait it out and see your plastic surgeon on a weekly basis.