Ever notice change in resisitance of vol control?

I currently have a DK Signature integrated. I've also had a Plinius 9200, Anthem seperates, Marsh seperates, McIntosh MA 6900, NAD M3. I've noticed something subtle in many if not all of my former preamps/ or integrated volume controls that I've had. Periodically as I've take my system through various adjustments, ie. changing power cords on an integrated or pre, or plugging and unplugging integrateds/preamps for various reasons, or even recently when I unplugged everything to clean and treat all connections, I noticed the "feel" of the volume control can change. By "feel" I mean the amount of resistance, for lack of a better word, that the volume control maintains. At one point in time the volume control will be a little more tight to turn it and then at another point because of adjustments like power cord changes or plugging/ unplugging an integrated or preamp, the volume control will have a looser feel and the tighter feel in turning it decreases. I know it sounds anal, but it's something I've noticed over the years in various preamp/ or integrated volume controls.

Anyone else notice this change in the firmness/feel when turning the volume control and know what accounts for it?

I'm not referring to anything like a volume control or pot wearing out. What I'm refering to is like a product of a voltage or electricity change in the preamp. Along with this change in the "feel" of the volume control there is always a change in the way the systems sounds -all apparently a result from disconnecting-reconnecting/plugging /unplugging the equipment. Sure, I know when adjustments are made like power cord changes, plugging and unplugging amps, etc. that the sound of the system will change and everything moved has to re-settle before the sound stablizes. But does this relate to the feel of the volume control too? Thanks