Seen it before on 72MHz.  Generally you must be very close, like just a few feet.  Sometime your own TX can cause twitching on your RX if the TX/RX are too close.  Normally unless the problem is isolated to one persons TX, or only one RX, I wouldn't worry about it.  Exactly how far was "near"?  Like 3 feet or 10 feet or 30 feet, etc?