Sorry, kinda late on this topic, but just a natural retracement in price. Prices shooting up that fast are due for a correction. Nothing to worry about.
The whole market was slow for the last 3 months and prices were only dropping. I blame this to the flippers who now had to undercut eachother in order to get rid of their cards.
We can see the market is already starting to gain momentum, much more cards are now being bought again and for reasonable prices