It's symptomatic of a failing battery -- if the battery is swelling, the first place you'll notice is with the touchpad (which is right above it).
(meanwhile, remove the base cover and check the battery -- if it's swelling, get it out of the system immediately and out of your home or office -- this IS a safety issue).
Thank you for answer, in the last months I had problem with battery and audio device that disconnect some times. Also today I feel the keyboard a little hard to press.
I don't have the tiny stellar screwdriver to open the back panel (and if I open it, do I not invalidate the warranty? remains me last days).
I am going to open a support ticket and call support tomorrow (when is active in my country).
Just a note: the page report "if you identify symptoms of a swollen battery such as bulging of the system chassis or palm rest", I am not at this point, how prove the problem at support?
They should allow a replacement for the battery anyway - they're replacing those (Simplo) batteries that haven't yet failed - as well as those that have.
You may want to invest in a Torx driver to remove those screws -- once the battery swells the probability of damage to the system is high.