I was using my 14 2.5 on my E-m10 sometime a few weeks ago and I noticed after a few minutes of walking around the display on the live view mode become dark. When I took a picture it would lighten up again when I pressed the shutter button to take the picture and then go back to the dark image in live view. I checked the front of the camera and noticed the aperture blades had closed up. They would open up and give the correct exposure when the shutter button was pressed and then return to this closed position. This only happened after a few minutes of normal use walking around. I turned off the camera, removed the battery for a while and turned it back on and still the same. I was in my normal PASM shooting modes, no special settings, DOF preview or any of that pressed. I've only had the chance to mount the camera once since then and it has not happened since then. I don't know if this means anything, maybe just a one off quirk with the camera or maybe it's a sign of the lens possibly on it's way to going bad.