I'm fairly certain that that is exactly how they do it. :}

Lava Lamps are Room Item's. :}

Glitches are bad and are not allowed to be exploited. :}

The knuffels leveling on their own can't be stopped/avoided. So they're not being intentionally exploited

I hadn't heard about knuffels doing such a thing. :}

They do sometimes. I think I see what she's talking about. It happened for a couple of mines, for a period of time they were leveling up faster than my other knuffel with apple+ice cream, although not as fast as the one with the lava lamp. Didn't quite understood I thought I missed something but then after few lvls they started to lvl just at the usual speed... Never knew what caused them to do this and stop suddenly.

Can't seem to find the thread.
Does sound like a bit of an unnerving bug though. :}