I can't speak specifically to the Earl Grey liquid, I haven't tried it yet, but in general TV liquids are better after they sit about a week or so. Of the flavors I have tried some were good right out of the box and some needed to "steep" for a week or two. Even the ones that were good right out of the box were better after a week or so.
Some vendors mix to order, TV is one of those vendors. The flavors need to sit a while to blend and settle into the final taste.