shift key randomly gets locked without being pressed (mbp 13" retina, late 2012)

I've been looking everywhere for answers for this problem, with no success (although many people raise similar questions on older models).

My MBP 13" retina 10.8.2 is new, clean, nothing spilled on it.

Ocassionally I connect it to external keyboard and mouse (USB or BT).

Regardless of that, sometimes the SHIFT key gets randomly locked - Without being pressed (whether the native keyboard, or when connected to external).

I could just be browsing the internet or be viewing a document in Word or GDocs, and suddenly - while mouse-scrolling - things will get selected, and the mouse-click becomes SHIFT-Click only.

When it happens, disconnecting/reconnecting the external keyboard or mouse has no effect - the problem persists.

The only workaround I found is to put it to SLEEP when it happens, and immediately wake it up.

The problem started a few weeks ago, and the behavior is completely random (it can happen twice in 10 minutes, or once a week).

Any ideas anyone?

PS - Apple Discussion Board - How come you forgot to put "Keyboard" as a Category for posts?