SPDR's buying and selling is a response to the buying and selling decisions of lots of retail investors rather than investment decisions made by a single entity. Retail investors always follow the market, so it should be no surprise if Gold ETFs are occasionally "whip-sawed".
I wouldn't read too much into this ....
.... and the paper gold price (gold futures) is always the same as the physical gold price, so the world is less interest than you think.