XS1 - Sensor dust.
Yeah it's an early sample with 14-serial, so technically it's "faulty". Just need to make these damn orbs to show! )))
A bit surprised though to discover such a "con" of non-removable-lens cameras. Can't do anything for dust and there isn't any sensor-shake-mechanism in X-S1 to keep the dust away. "Luckily" there are very little chances for the camera to live long enough for the dust to become a real issue - given the conditions it's used in. So I won't have to learn to disassemble it for cleaning once the warranty is out...)))