Glitching Question?
What you call glitching is normal with no signal to the receiver. You ALWAYS turn the transmitter on first and receiver on next. Always, turn the receiver off first and then the transmitter. What you experienced is the receiver searching for a signal, the automatic gain control (agc) in the receiver is just converting stray RF into an action and thus telling the servos to do something. The harm that can come from having the receiver/servos turned on without the transmitter signal is that the servo(s) may rotate all the way in one direction and stall the motor in the servo which could cause it to fail. Or, could cause the servo to move a control surface to its limit and also cause a motor stall or destroy the gear drive in the servo. You may want to install an on/off switch so you don't have to disconnect the battery every time.