Hello !
I don't think that your K-x or lens is faulty. It's very unlikely, just relax
With the picture we can't help you much without the EXIFs to tell us what were your parameters (iso, aperture, etc ...)
I suggest you,
in bright days like those in this picture, is tu put your K-x in Av mode, and select f8 with auto iso between 100 and 800.
So you will have much more crispy pictures.
For the street picture, you could even go to f11 or f16 to get bigger dept of field.
Give us the exifs to get more help.