There is a) something wrong with your machine, or b) more probably the mix
was too stiff and the machine was labouring. I've had 3 machines and they
barely move, just a little shake. The rubber feet stop any creep totally.
If you think it will happen again just put the heaviest weight you have
between the machine and the edge of your top. If it moves that you
definitely have a faulty machine.
Brian
ps make sure there is no oil or grease under the machine; wipe the
countertop with detergent, and the rubber feet.