She has better English than many foreigners I know who have been living in the US for >5 years, and better than the foreign language skills of many Americans I know who have lived overseas for that long.
I'm pretty sure you know this. Yes, in Beijing, Shanghai, Shenzhen, it is not uncommon. But go to a smaller city, and some people will treat you like a rare Panda. I was in 九寨沟 one time during 清明节 and a lot of out of town people were there on vacation, some of who had never met a 外国人 in person before, but after they heard me speaking, a lot of people kept coming up and asking to have a photo with me, offering too much praise for my terrible Mandarin, and intensely curious how I learned.
I'm glad to see so many people following in the footsteps of 大山, but we have a ways to go before the asymmetry is more balanced and a Westerner speaking Chinese is no longer surprising enough to be on a talent show.
China has no problem finding foreigners who speak good Chinese like they did in the 90s. Likewise, they are a bit unnerved when the American ambassador speaks fluent mandarin like Huntsman did, or like various prime ministers of austrailia are ought to these days. They definitely exist, and if some random white (or black or Indian, etc...) guy/gal breaks out mandarin in some random context, well, it really isn’t amazing anymore.
If you visit a tier 88 city in china, the fact that you are a foreigner at all is amazing, this has little to do with your mandarin skills. Now hit the bath house with them and it’s double amazing.