Likely not Gaban.
If Roger wanted to hide the 4th Poneglyph like that, Rayleigh could've done it. It doesnt make sense to me that Ray is chilling in Sabaody while Gaban is busy on a ship hiding a Poneglyph.
Also Oda loves his patterns, he introduced Roger in ch. 1, Rayleigh in ch. 500. So if he wanted to bring Gaban into the story, he would've done it around ch. 1000.