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).

See here:

en.community.dell.com/.../20022402

(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.

Ok, Thanks