Does this sound like a mechanical failure of the switch?
It's possible a mechanical failure could cause this behaviour. Under normal circumstances the attack on the Boss circuit is quite rapid. There is a release time before you can press it again but that is quite short as well.
I am just need to get another switch and try eh?
Well that would be a good test, perhaps temporarily solder a cheap push button across the existing switch and test is with finger presses.
I'm not aware of a common problem like that.