I have an intermittent vibration sound that comes from the area to the left of the steering column when I drive over uneven surfaces. It can be a slow or high speeds. I don't hear it a lot, but just enough (maybe 5% of the time) that it's really annoying especially since I can't figure out where it's coming from!!! I want to say it's maybe from the left A/C vent but not sure. I think I have seen others post about having a similar issue but I don't recall seeing a definitive answer to what is the cause. I'm scheduled to take it to my SC but of course I'm sure they won't be able to replicate the problem on their short test drive. Thoughts?