Actually it was added to big exchanges. More people knew about this project. Raiblocks was in the shadow for long period of time and looked very undervalued.
I actually have thought the same thing, why XRB price is mooning. Now if my memory serves me right, XRB was recently added to two major exchanges - RightBTC and KuCoin. Apart from the two, it also won the Binance voting competition and will soon be listed on their exchange.
So taking these into consideration, probably these are some of the reasons that trigger the sudden upsurge in its price.