Per Wolfram Alpha, sulfur is 4.62 times heavier; the earth is 0.002% lithium, so it would experience a net gain of 3.62 * mass of earth * 0.00002, or 4.3e20kg. That's 7.24e-5 times heavier, so not much in the grand scheme of things.
Note that I'm neither a chemist, a physicist, or an astronomer, so I make no guarantee that I did this right.
Edit: misplaced decimal
Is this a common problem? I've almost never had a burrito fall apart on me unless it outright rips--I once made the mistake of ordering a burrito in Scotland, and that was pretty formless, but it was also less a burrito and more an embarrassment hiding under an ill-fitting tortilla.