Gaskets have a bad tendency to overheat and then break due to engines that run too hot. As the metal heats up, it expands and then contracts when it cools, which can weaken from the metal just a little bit each time. Various chemicals that come in contact with the gaskets can also lead to their breakdown over time. You indicate another gasket failure by checking your engine oil. If it looks like chocolate milk or is watery and bubbly, then you’ve likely got coolant mixed into your oil. When you have one gasket that needs to be replaced, it’s best to replace them all at once. Whatever environmental factor that caused one of them to fail is likely to affect other gaskets, and pre-emptively replacing them all can save you expensive repairs down the road. Be sure to check the torque on your head gasket when you’re replacing it – even a new one may require re-torqueing to assure it’s resilient and can continue service. Assure that the head and the block are good and flat before putting a gasket back on. A gasket needs a flat surface to seal correctly.