The strangest thing happened to me earlier...

When I usually play with my vibrator I have about 4-6 orgasms. After the 6th one today it um,well,just kept going. It felt so good...I lost track after a while. After about the 7th one or so they were all very minor, but nonetheless orgasms. I think there about 20 in all, possibly more. My questions are: 1) How many orgasms do you normally when masturbating? 2) has anything like this ever happened to you? 3) Should I worry or just accept this as an act of serendipity?