I'm assuming you were at the point of either just adding the eggs, or cooking the mixture on the stove? When adding eggs to something warmer, the eggs need to be heated first by adding some of the warmer mixture to them. This also makes a difference in that as you're cooking it, they don't tend to cook into chunks. Eggs need a gradual rise in temperature, and too much heat can also cause it. It's very common, and happens to a lot of people. A lot of people end up sieving (straining) puddings and custards.