My facts may have been, old like me, but it was true during the Apollo years.
It makes sense, though. Any harmonic system can be affected by more than one rhythm. In the case of a gravity driven harmonic, the orbital cycle is likely to fluctuate as the orbit degrades (falls closer), but speeds up, causing a greater inertial force to move the orbiting body back outward.
As with a pendulum, the farther from the center of rotation, the slower the travel along the arc of orbit the bob will move. The harmonic volume can't be maintained in a orbit like it would be with a pendulum swing, so the period speeds up or slows down to maintain the same energy level. I would be very surprised if the moon did not get closer, then farther away, through the months, years, millenia. It is likely that it also has larger extremes in its cycles causing things like, "Great Floods" and changing weather events on Earth. The Sun's activities, I'm sure, also drive the system a little. Just like there are moon driven tides on Earth's surface, I'll bet there are also moon driven tides in the core that may cause things like El Niño, wandering magnetic pole, and cycles of hightened volcanic activity. The system is way to complex to be able to point to one cause for most natural rhythms on Earth.
But, I would suggest waxing your boat because you never know when you might get in an accident, and you don't want to get caught in the equivalent of "dirty nautical underwear" when you are taken to the boat hospital.
-Will