In playing the flute, Krsna was very expert, and the gopis were captivated by the sound vibration, which was not only attractive to them but to all the living creatures who heard it. KRSNA BOOK, p.147.
Brahmā addressed Lord Kṛṣṇa as Acyuta because the Lord is never forgetful of a little service rendered by His devotee. He is so kind and affectionate towards His devotees that a little service by them is accepted by Him as a great deal. Brahmā has certainly rendered much service to the Lord. As the supreme personality in charge of this particular universe, he is, without a doubt, a faithful servant of Kṛṣṇa; therefore he could appease Kṛṣṇa.