We have random pipe pinging noises in our master bedroom bath mostly in the early morning between 3 and 6. They can be faint and several seconds or louder, trailing off to nothing. They are never the same. Last night this occurred at least 15 times over 2 hours. Pipes have been checked and there's no problem that we can see. Our house is built on ledge with lots of rocks and chipmunks under the front lawn (which slopes down). Could these critters be playing or running on the pipes? We've lived here for 4 years and this started only 2 months ago. I need to get some sleep. Thanks for any thoughts on this problem. Sue