PAL cradles produce logspam by repeatedly re-rendering drag cube

[Wyzard256]

Having PAL cradles in physics range sometimes produces the log message "DragCubeSystem: Rendering procedural drag for PAL.Cradle250" every second. (Presumably this would happen with PAL.Cradle375 as well, but I haven't tested that.)

This doesn't happen consistently, and I've had trouble reproducing it on the launchpad, but I've attached a save file with a Minmus base where it happens consistently. I've tested the save in a clean install of KSP 1.3.1 (Steam version on Linux) with no mods except MKS 0.53.0 (and its bundled dependencies), updated with the USI Tools 0.10.1 bugfix release.