Trackpad gesture that minimizes all windows? This has been driving me nuts for close to a year. I hope someone can tell me what triggers it. I've searched many times over several months and have never found any mention of it.

I use an MBP running OS X 10.8.3 with external monitors, external keyboard and external trackpad. Occasionally while I am manipulating windows with the trackpad (usually moving them by dragging, I think) all of the open windows for all apps will begin minimizing to the dock, one at a time, using the genie effect. Depending on the number of windows I have open, this can take several seconds. I have no idea what, specifically, I'm doing that triggers this behavior.

It is NOT "show desktop" -- the windows definitely fly down to the dock and are minimized, they do not slide to the edges of the screen. The windows are not hidden -- they don't come back with cmd-tab, for example, and they don't disappear instantly -- they "genie" down to the dock. The closest I've found is option-cmd-M, except that it only minimizes windows for the current app -- the behavior I'm asking about minimizes ALL windows from ALL apps.

Help? Please? Thanks!
I've found no default bindings that would make this occur, but I have found an application that possibly could be triggering what's occuring. There is a background application called MagicPrefs which allows for the addition of non-default bindings. MagicPrefs would also allow you to bind AppleScript to things like this as well.