On my '69 the horn buttons are quite sensitive and when I am backing up and turning while looking over my shoulder I find that my arm brushes the buttons just enough to beep the horn at inopportune moments ('69 deluxe wheel).

I believe the springs are just weak in the switches on my car. It takes only the slightest contact to sound the horns. Are yours truly random, or is there the possiblity that when you are turning you make slight contact?