x100 overexposes most of the shots :-(

I thought my X100 had SAB. I too looked at the lens to see it the blades stopped down. At first I could see nothing. And then I noted they didn't stop down to the same place - or, seemingly, as quickly. I hemed and hawed, took it in - and, yup, SAB. Fuji UK turned it around on the same day.
--
John