99 5spd vr6

Once in awhile when I'm braking, usually from high speeds, the vehicle shudders. I assumed this meant that I needed new brake pads.

I took a look at the passenger side today. The rear pad still has a lot of life left about a 1/4 inch, no searing, looks normal. Front disc has no scarring, brake pads are thick with a lot of life left, however the inner pad is slightly thicker than the outer. Also the inner side of the caliper looks a lot worse for wear.

I'm no expert, so I had my Dad take a look. He said everything looked good. The only thing he could think of was that the front inner brake pad side of the caliper may have seized up. Which could be the cause of the difference in front brake pad thicknesses.

Is there anything else that could cause the shudder that I should look into? Could it be the caliper?