[mrpackerguy]

With my GRiiix in my palm, lens to the ceiling, if I gently move my hand back and forth to the left and right, I can feel the whole inside mechanism shift left and right. Is that right? None of my DSLRs do that. My wife's nikon P&S doesn't do that.

[wadge22]

I haven't heard of it specifically on the GR IIIx, but it does happen on the K1 series. Exactly as you describe. It's just the shake reduction mechanism.
I'm (confidently) guessing that you have nothing at all to worry about. And you're in good company being concerned; the question comes up frequently from users who get a new camera and are worried something might be wrong with their gear. Nothing is wrong! Enjoy your camera!

[aaacb]

It's the ibis (sensor stabilization), which moves freely when the camera's off. Perfectly normal

[JPT]

As mentioned by the two previous posters, this is the way that the sensor shift stabilization works. The sensor is free to slide left-right-up-down while the power is off. When the power is switched on, the electromagnets activate to hold the sensor in position.

The best way to illustrate this is to hold the camera as normal with the lens facing forward. Rotate it around the lens axis to the 45 degree point each way with the power off. You can the sensor sliding left and right. If you turn the power on and repeat, there is no sliding.

With the power on, you can sometimes hear a faint whirring sound as you move the camera and the SR system continually adjusts to keep up with your movement. But it's so faint that you'd only hear that in a quiet environment.

All of this is normal for a GR or Pentax DSLR.

[eles]

Probably silly questions, but here goes:

For cameras with shake reduction/freely moving sensors, when the camera is off, does it matter how the camera is oriented for long periods of time, such as leaving the camera in vertical orientation on a tripod for several days, or perhaps face-down when packed in a bag? Is there an ideal orientation for storage?

Not that I'd trade shake reduction for a possibly longer camera life-span, but how much extra wear and tear is there from the freely moving sensor when the camera is off and subjected to vibrations from being in/on a moving car/bicycle/train/etc?

[AgentL]

Probably silly questions, but here goes:

For cameras with shake reduction/freely moving sensors, when the camera is off, does it matter how the camera is oriented for long periods of time, such as leaving the camera in vertical orientation on a tripod for several days, or perhaps face-down when packed in a bag? Is there an ideal orientation for storage?

Not that I'd trade shake reduction for a possibly longer camera life-span, but how much extra wear and tear is there from the freely moving sensor when the camera is off and subjected to vibrations from being in/on a moving car/bicycle/train/etc?

There's no difference how the camera is oriented when off. The sensor unit has space all around it to allow freedom of movement when it's powered on and the IBIS is engaged, it can rest anywhere inside this without issue. There are many camera models with IBIS now that have free-floating sensor units when turned off. I first noticed this with my Panasonic GX85 in 2016, but that certainly wasn't the first and many subsequent models have come out in numerous formats. So I wouldn't worry about it!