Mun Orbital Decay?

[kiwinanday]

First question, usually able to sort things out without needing to make a post:

I left a craft in [what I thought was] a stable 300km circular orbit around the Mun last night, with Mechjeb holding the craft prograde. I wake up this morning to notifications that it crashed into the surface! I had all engines shutdown, so there's no chance it was caused by errant throttle, and Mun has no atmosphere (even if it did, I would have parked well above it); so what caused my craft to lose orbit? I've left crafts in Kerbin orbit overnight, and not lost them, so is this just a bug with the Mun, or a general bug that needs fixing?

Jeb's dead, baby.

 

Edit: if it makes a difference, the craft in question was a 2.5m fuel depot (fuel tank, solar panels, batteries, monopropellant—all the necessities to resupply in orbit) with a smaller SSTO docked to one side, so the controlling module was not directly in line with the cG, though it was parallel on all axis; see attachment for pic (sorry it's dark, Kerbin was eclipsing the sun, and we were about to head behind the Mun)

 

Mods running (though I don't see how they'd cause this) include:

Mechjeb, KW redux, B9, FAR, KSPI, RPM, KJR, Chatterer, Hangar Extender, and RCS Aid. 

Edited May 7, 2016 by kiwinanday
Adding information

[purpletarget]

There is a general bug where orbits in flight aren't entirely stable. 

http://bugs.kerbalspaceprogram.com/issues/9619

However, 300 km over the Mun shouldn't have degraded quite that quickly, and have no illumination if MJ may have done something while you were away....
 

Leave your craft on rails via warp out at KSC scene, and it should behave better.

[kiwinanday]

@purpletarget

Thanks, I'll go back to KSC until the bug is patched; I used to leave 0.25 running overnight, as Chatterer helps me sleep. 

I don't suspect mechjeb directly, as I don't know why having it hold prograde vs having SAS hold prograde would make a difference, but I can't know, as I wasn't awake at the time. 

[bewing]

Actually, I was doing an orbit last night, and my 16km Ap was changing by 100m/s. It was, in fact, rising in this case ... but still. 300km in 8 hours can happen pretty easily.