XF1 - same settings, different exposure

It can't be said that it's the model's fault,
for the time being, let's assume it's a specific malfunction.

I tested further and found it to be the shutter mechanism's fault -
See this batch I took on the way to work this morning, using aperture priority,
it's obvious that the shutter speed remains steady at about 1/25 throughout
the whole batch, even though the reporter speed changes in each photo.

I noticed that this happens more often when the camera is cold.
Once warm in my hands, exposures are correct and photos are very nice.
Not that it's so cold out there, about 15 degrees Celsius.

-eyalg