Is my tetra dying? Its looking a tad faded and its constantly swimming towards the surface.?

i just bought 4 neons today for my new 10 gallon setup and 1 seems a bit under the weather as of being in the tank for about 6-7 hours. theyve all been fine but now this one is swimming towards the top and looking much less shiny than the rest, could it be that he is ill or maybe its the way the light is hitting him? when he swims down more his color sort of comes back...