First off, it is extremely bad and i do not know just how the FBI was not onto this chap the day he showed up. If they were doing their job, they were and kept him in the loop deliberately. This is more normal spy-craft. If not then start firing the fools.
More seriously though, this is the tip of the iceberg in terms of Sen. Feinstein if i am reading the Intel correctly. The rest is likely to come out soon as well as it will be embarrassing to the DEMS as if they are not already embarrassed enough.
I have dealt with hundreds of Chinese over the years and this has included the odd spy as well. No, they did not tell me either. Recall every student leaving China gets an exit interview and contact information and may well also have a local handler here to assist him. Most of this does not stick but greed and opportunity will work wonders.
There is no need to be paranoid, but you must never recruit a foreign national to handle sensitive information normally. This is simply because he will be open to family blackmail however honest. So even before you do a security review, just why was a Chinese national ever considered for the position of driver in the first instance? Did Feinstein accept him as part of an arrangement?.