If you just got him yesterday, then yes, he's probably getting used to everything, including his new tank, new water, new food, and you! It took my last betta about 2 weeks to get used to his new home. For the first two weeks, he hid a lot, seemed really shy, and most of the time, he looked more like a wilted lettuce leaf than a fish. I've have him for three weeks now, and these days, he spends most of his time flirting with the female who lives in a tank adjacent to his. Also, his colors have become more vibrant, and he no longer looks like a wilting piece of lettuce. (He's my current avatar picture.)
Good luck with your new fish!