Pure gallium with lower melting point?
It's possible that the gallium is not as pure as advertised. If it has (say) some indium as an impurity, the indium-gallium alloy would have a lower melting point, potentially below room temperature.

I thought that partial freezing might have crystallized out more pure gallium, and left less pure gallium as the melt, but I'm not sure that's how indium-gallium alloys work. I made a few grams of the alloy, and I never saw any such behavior in it -- then again, I never experimented much along those lines.