I got my valves adjusted last week and I am expeiriencing a weird problem. When I first start my car it is fine. The problem only happens if I start my car after it had been ran to normal temp.( For example) I go to the grocery store, come back out start my car, and my engine makes this clack clack sound for like 20 secs or so then goes away. It is coming directly from my valve cover, and it did not do this before I got my valves adjusted. Can someone please help???