I have the same wah and sometimes it cuts out when I disengage the effect...Dunno why either.
Yes it happens. My guess is that is because of the footswitch button. When it doesen't get pressed properly or sloppy it tends to "jam" up a bit so to speak. But this happens rarely, happened to me on gigs maybe 2 times, and it was not too bad (but if you have some earplugs and no monitoring...it can get pretty interesting
)