Yes, I am, because I no longer meet the conditions to Hide in that room (well, assuming it's well-lit). But I haven't lost concealment or invisibility or any of the other things true seeing deals with. They're different cases entirely - all Hide in Plain Sight does is extend the conditions under which you can hide: you can hide with only a bit in the way of nearby shadows, and you can hide when being observed. It does nothing at all to actually conceal you. In fact, Hide in Plain Sight is always "on", whether you are actually hiding or not; it isn't something I specifically elect to use. Even aside from that, it lets you hide even while being observed; it doesn't magically grant you pseudo-concealment. It represents supernatural skill at hiding, not anything that true seeing counters.