Checking the shots at 58mm and 62mm, I can see no difference in the camera settings. The EXIF data states that both were taken at the same aperture, shutter speed and ISO, and that other things like Picture Control were identical.
My only conclusion is that for some reason your lens is not stopping down to the pre-set aperture when used at longer focal lengths. I'm afraid I have no idea why that could happen, apart from a damaged lens. You could test out this theory by taking a similar series of test images in aperture priority with the lens at f/2.8, as suggested in reply #18 above. That would eliminate any stopping down, and the images at 58mm and 62mm should not appear wildly different in exposure.