Reeva Steenkamp

We can't quite put our finger on it ... but there was something strange about our encounter with "Blade Runner" Oscar Pistorius in Los Angeles back in October ... something ... creepy. On the surface, he was totally polite with our camera guy as he left dinner at Mercato di Vetro with a friend ...…

Oscar Pistorius -- the Olympian now accused of murdering his model girlfriend -- was never violent toward her in the past -- this according to a source who worked closely with the victim in her modeling career. The source tells TMZ ... she was with Reeva Steenkamp "a lot" during the months she was…