I have seen this many times with the ADV and 950SM engine. If you look on the right side of the engine and behind the rear cylinder you will find small oil passage plugs in the top of the engine case. I have seen where these do not get pressed in properly and begin to leak. There is a special method to repair the problem without replacing the engines cases that works maybe 85% of the time.
Not to say that this is the problem noted with the SDR, as the cases are sand cast and I am sure that there can be porosity in the casting.
Either way, sucks to happen on a new (or used) bike