The pedal "axles" are tapered on one end allowing movement, it's an odd design but they must have had a reason for it.
With the movement you can actually push the pedal too far and the potentiometer slips out of its little pocket. This makes it operate ineffectively and often you get spiking near the top of the range or you don't get the full range at all. The autocalibrating nature of the device can then report a false centre and you might end up with a little brake always on, or a little bit of throttle.
Although your operation has fixed your problem, I fear it is only a temporary respite. A more permanent fix requires some method of stopping the pots from lifting out of their pocket/receptacle. There's a dozen ways of doing that, but it is important not to glue the pot or attach it too solidy or it will eventually snap.
Perhaps the best solution I've heard is to cut small cubes of foam rubber (you could use a new kitchen sponge or something inexpensive like that) that fit snug inside the pot's little pocket. Stick the pot into the foam cube so that it can hardly move, a little movement is ok, we are just trying to keep it from lifting out. If you've done the job right it should last a long time.
You could address the axle problem while you are there, clean off the lubricant and use thick tape to reduce the amount of play around the pedal shaft (axle).
If you want to service the pots spray (blast them!) with contact cleaner
only (available from your electronics store), don't use automotive or engineering degreasers, sprays or lubricants.
My first set of Momo pedals completed almost 50 000 LFS miles, not to mention other games that I used them in. But many repair jobs were required.