There does seem to be a Lens Zoom Servo issue some people are experiencing with the EX1. There seems to be a range of experience from near complete failure of the zoom servo to stepping or stopping in low speed zooms.
Another user just reported this buried in another thread on this forum.
I sent my camera to Sony San Jose. When talking to them they mentioned an "upgrade" rather than a repair, which involved replacing the entire lens. They stated that they still had issues. They're replacing my camera (getting the new one on Monday). They mentioned having a back log of cameras in on two issues of which one is the lens servo issue.
Really do give a good thorough check of your lens zoom servo. Again many/most apparently aren't experiencing the issue but given the range the issue may exhibit itself one might want to do a careful tech check.