Well same issue, autofocus decided to stop working.
(in Canada we have 2 years warranty but I've got this lens for less than a year).
As many said, I reported that its sad, as I really love this amazing lens... will look forward to get it back asap
So after this I will have to look into my 16-50 DA* that is working perfectly for the
image and focus but as many also reported I feel a bit of stiffness when I get near 28mm
but as long as my pics are nice I'm not saying anything...