I once sat down a a machine a hit a big winner (1000 credits) almost right away. However, I kept playing and wouldn't you know I hit another one just a little later. While waiting to be paid I sat at the next machine and hit another 1000 credit jackpot. After both were paid I went back to the original machine and hit yet another 1000 credit jackpot. All of these occurred in less than an hour.
By Alan's logic I should expect this to happen every time I play.