I had a very noticeable wobble at 72-77mph and couldnt figure out why. Today I took my car in for the some service (Oil Change and Registration was also due). After the tech had finished he said that my tires were all reading a little different pressure. He adjusted and I went on my way. Needless to say the car tracks perfect and is smooth as can be. When I got home I looked at my "trusty" tire pressure gauge on my compressor and it was actually bent so the pressure monitor would only come out to a certain point then it was stuck. I had not been able to read this for the past few months so I was a little off. When I say a little, it was not visible by looking at the tires, but it was enough to throw the ride out of balance.
That "trusty" pressure gauge has since been replaced.
Oh, I explained this to my wife and she admitted to running over the hose/gauge a few months ago with her Hummer.