Sounds like something is building a static charge, either the heli or your body.
Try touching the engine or the ground side of the glow connector with one hand while putting on your glow starter with the other.
If it doesn't glitch your servos then it is probably static discharging from your body.
I have not had this problem with my helis but did have the same thing with a car, especially when wearing a nylon jacket.
If it is static from your body then it's nothing to be concerned about, otherwise, I would try a different RX and make sure your antenna is located away from any servo leads or metal.