On my way to Costco and the car starts to really rock and roll at the stop sign. It was really scary. I arrived in the Costco parking lot, called the car dealer to see if it was safe to drive the car...what could this possibly be...just two weeks after my first year tune up?? Car would not repeat the behaviour despite a bit of careering in the lot and quick stops and starts, tires looked okay. I was told to bring it in immediately if it occurred again. I get home to find out we've had an EARTHQUAKE! I felt the earth move under my car! Most unsettling, but I'm glad the car is fine - so are we all.