Hi Empire:

First, every woman's body is unique, so there are no rules carved in stone on orgasms.

Second, your use of sex toys does not hurt you, nor cause this.  My wife enjoys them and we both use them on her.  She even uses them on herself in front of me.

Your body has become more sexually sensative, and its caused you pleasure, but also suprize.  Its really OK. 

My wife didn't have orgasms until about 35, and but when she started, they were very strong and frequent.  Its possible that your sitting position may have triggered your clitoris and your body just reacted.  I suspect your vaginal area is very sensative, and that you may be able to reach an orgasm sooner than many women.  Most women would consider you lucky, as they have difficult times reaching orgasm.

You may want to share this new experience with your husband.  I really enjoy making my wife orgasm and find it great that she can do it so easily and so often.  It adds alot to our sex life, and you may find the same.