There is apparently a safety issue with SOME Bosch PWS and GWS Angle Grinders. See http://www.electricalsafetyfirst.org.uk/product-recalls/2017/01/bosch-pws-and-gws-angle-grinders/ for further details.
Now that is something you don't often see with Bosch. Only grinders manufactured between June and August 2016.
What appears more scary is the reason they were recalled "During use the cutting/grinding disc may detach" Although it is unusual for Bosch grinders.