I believe that the letter is
stressing the point about the button on the way up, rather than simply not mentioning it at all.
Just as well they didn't include everything else you shouldn't do at the same time too - would have been a long letter!
"Pull the lever upwards. Do not touch the button, fiddle with the electric windows or mirrors, or adjust the heating, stereo or sat-nav (where fitted) controls. Caution, contents may be hot or contain nuts. Objects in your mirror may appear closer than they are. Re-fitting is the reversal of the removal process.
To release, push the button"
