It took me awhile to figure out what this noise was. A few weeks ago I told the Hubs that I thought there may be a loose shingle on the roof because I kept hearing this thumping noise coming from the ceiling. We just had our roof replaced about 2 years ago because we used to have this problem all the time. Combine a west facing house with a cheap roofing job and it was a recipe for disaster. As time went on and I heard this noise even on calm sunny days, I started freaking out. Was someone on our roof? Was some disgruntled neighbor kid perpetually kicking a soccer ball at our house? Then with a slight adjustment to our video monitor I'd start to see two little feet lifted high that would disappear out of view about the exact same time I heard the noise.
This pretty much eliminates our need for the video monitor we spent $140 on. I can tell by just listening whether she's awake or not. These chubby little thighs mean business.