Gooey tailgate release button

Hi all, first post on this forum! Yesterday I became a new proud owner of 2007 Prius. The car is like new, 40k miles, everything seems toi be working perfectly, but....

when I put my hand on the tailgate release and pressed the button I noticed a gooey feeling, like someone stuck chewing gum or playdough in there, and I had black residue left on my fingers. Since I never owned Prius before I have nothing to compare with as to what this button cover should look and feel like. I attached a pic where you can see the black cover is all messy.

Any ideas? Should I just scrape all the black stuff? What could have happened to it? What should it look like?