Is it normal to experience a continuous orgasm from vibrations?

I have a vibrator that's really strong and is used to massage your back and legs etc. Well, I actually use it for sexual pleasure. I'm a guy and what I do is I turn the vibrator on and hold it against the edge of my mattress as I sit on my bed. The vibrations are so strong that they vibrate my whole mattress while I'm sitting on my bed. I kid you not, I was having orgasm after orgasm from just my mattress vibrating. I know it's because it's stimulating my prostate externally. The weird thing is that I've always heard about the Aneros or other sex toys that men can use to insert into their anus and it vibrates the prostate that way but has anyone ever heard of being stimulated and having multiple orgasms just from sitting on a mattress on the bed as the vibrator vibrates the bed???? I'm not complaining cause it was heaven feeling the orgasms but is this normal or am I just more sensitive to the stimulation? I don't know if it has anything to do with how some guys get stimulated from other vibration sources like deep bass from a sound system or a subwoofer.