Corn shaking his tail

[jejton]

I have a corn snake that is about 3 or 4 years old whom I adopted about 2 years ago. I dont handle him much but he usually allows me too as much as a snake will. He doesnt usually just allow me to grab him but once I do he is docile enough, never struck or anything. Lately I noticed a new behavior though. When I reach into his cage, as he is slithering around he starts vibrating his tail. I have read of certain snakes doing this as a defense. The idea is that the tail vibrating against leaf litter mimicks the sound of a rattler's tail. Has anyone experienced their corn doing this? Should I avoid handling him when he does this or should I gently handle him more often to get him more accustomed?