I outlined the area where you will find the date of manufacture.
If you have an older radio with the extendible antenna, the older none-adjustable sliders, matt chrome surface around the gimbals and matt chrome buttons, yours might be produced in 2009.
I've got two MY 2009 radios and both started to show corrosion (green rust) around the charger plug quite early. Also, my first one got white spots like the radios in the link I provided above.
It looks like something went wrong during the production process/chrome-plating of some of the very early SD-10s. Or my hand sweat is like acid rain.
As I tried to show, even car manufactures like BMW do have problems with chrome-plating.
I do not know whether your radio is already out of warranty. If you need to replace the case of your radio, I would upgrade the whole thing to the newer standard (new sliders and case).