Q: Brake, VSC and ABS lights on, grinding noise during braking

Hello. My car has gone around 110,000 miles. The dashboard has been showing several lights illuminated in the last few months. There is the brake warning light illuminated red that would show sporadically. Also, the ABS and VSC lights would be illuminated occasionally. When I went to the shop to get my oil changed, the mechanic had my brake pads replaced because they were worn. After that, only the brake warning light would sometimes turn on. While I was driving on one occasion, I made a U-turn and applied the brakes. There was a loud grinding noise. It seemed as though I couldn't brake as well as I used to. The noise was noticeable several times in row while I was applying the brakes and the three lights were on--the brake warning light, VCS and ABS lights. When I went back to the mechanic, he said that there was air in the brake lines. They bled the system. Could that possibly cause that loud grinding? I am about to take on long-distance driving and I was wondering if it is really safe to drive the car now. Thank you.