The Fujifilm X100 is an amazing camera (and you can read our extensive real world review here), but it is plagued by one well documented manufacturing defect — at least the early batches of this mirrorless camera. The ‘sticky aperture blade’ issue results in the lens diaphragm blades not closing down as they should and hence leaving the aperture wide-open even at increasing f-numbers f/8, f/11 and f/16.
The first indication that your X100 may be suffering from the sticky blade problem would be if it tends to overexpose images. Because the aperture doesn’t close as it should on high f-numbers, more light reaches the sensor and results in an overexposed image. The issue won’t be apparent at wide apertures, like f/2 for example.