One thing moving to mirrorless is that you are supposed to turn off most bodies before swapping lenses. Most mirrorless systems close the shutter when turned off (as well as Canon stopping down the aperture and shifting focus to infinity) and you are only supposed to swap lenses while the body is off so as to lessen the exposure of the sensor to dust and contamination.
With DSLRs, the mirror box makes this much less of a problem, and the mirror being dusty isn't really a huge issue. It's something I have definitely had to become much more attentive of moving to mirrorless systems.