That was a just glint on his glasses, that could have been nothing. There’s no solid visuals for FS not unless Oda shows the actual scene like what he was doing in WCI and Shanks’ case.
Logically, Gaban would stop when he sees that Luffy finally takes him seriously. Add in Zoro who was rushing him and you won’t need FS to stop fucking around lol, that’s basic survival instincts.
Oda always gives that confirmation of an ability, he just did it this chapter. Now we know that the glint on the glasses could have been a tease.