Yes, that's right. As you learned in the lesson 5 in Genki, が works as the object marker for 好きだ/嫌いだ. It's the same also for other adjectives that express feelings/emotions/sense (e.g. 怖い, 憎い, 痛い), the -tai form of verbs, the potential form of verbs (書ける, 話せる, 食べられる) or state verbs (わかる, 要る, できる). You will learn about the -tai form in the lesson 11.