Today I saw that I had 1000 BAT and 0.60 USD, some hours after it said 0.58 (but the BAT amount was the same). Now I have 1060 BAT and 0.59 USD. I also experienced problems with the Brave Rewards card, as it says on some occasions that I have 0 BAT.
BAT coin goes up and down in value.
@CoolGuy001 nothing to worry, like any other cryptocurrency bat value change periodically.