That's not post reboot - the Doctor has always been a thief, even to the tardis and who knows what inside <g> He never had a compunction against stealing anything if he was curious about it, to do some science experiments with.
His very first act after regenerating into Jon Pertwee was stealing everything left and right, from clothes to cars, and was very put out when the Brigadier insisted the car et all had to be returned. He then demanded that the Brigadier replace everything he rightfully stole, as if the Brigadier owed him for taking things back. His last act before regenerating was all about a crystal he stole from a cave that he wasn't welcome in, and his reaction was the same as it had been since the first Doctor - he thought it was curious and worth experimenting on, why shouldn't he take it?
As for the gold dust, I was pointing out he handed it out like he couldn't quite understand money, not saying it was stolen .. but now that you bring it up, he likely lifted it out of some mine or something <g>, maybe with Cybermen in mind.
Maybe you've missed over the years his pride in pick pocketing in all regenerations, and complete lack of understanding "some one else's", but it's been an ongoing character trait for decades.