Digital camera vibrates after taking pictures.

I took 2 pictures, one at a time, I would stop to look at the picture - and I'm holding the camera with my pinkie fingers on both sides and my thumbs hold half and half, the bottom of the camera.
That's when it vibrated. I took another same place picture, held the camera the same way to look at the picture, it starts vibrating.
I later went to another location and took a photo and again it vibrated. 3 times in one night. Fully charged battery. Can this happen and why?

Thanks,
Carole