It's absolutely ok - in fact, he did you a favor! A bit of dirt in the compost actually helps the compost break down, as it contains an abundance of microorganisms needed for decay. Most instructions for compost-pile-building suggest that you add a shovel full or two of dirt, but a little more won't hurt either. If you feel like the clay soil on top is weighing your pile down (which it might be), just turn your pile to incorporate the dirt and get some air into the pile. Clay soil is actually full of nutrients, so it will just add to the pile all of it's good qualities :).Remember to keep the pile as damp as a wrung out sponge, and try to add green/browns in a 2:1 ratio and you should be good! If you have any other questions, feel free to call the Master Composters "Rotline" (really!) at ###-###-####. I'm a Master Gardener for Santa Clara County and if you have gardening questions, our hotline is ###-###-####, with staffing to answer your questions M-F, 9:30-12:30 :). Good luck!