My suspicion is that the silicone will shrink a tiny bit as it dries and pull away from the tile. It might depend on the type of silicone used. I'd keep a very close eye on it, you might have to rip it out and do it over.

I did see a neat trick recently: the guy duct taped a spoon to the tube of silicone, so the spoon trailed the nozzle. So as he went along and squeezed the silicone out, the spoon was taped in a position such that it was following along and removing any unnecessary silicone, leaving behind a clean line of sealant.