I agree with Hoosier, it is primarily a diffusion thing. The way I see it, flavor molecules can sort of clump together in a concentrated flavoring, and sometimes, with some flavors, it takes a little time for them to open up. The thinner the base, the more they open up, and the faster. Some add a little PGA, which really adds to the flavor bloom. But I digress, as this is not a steeping time thing.
That all said, I noted an interesting thing with some 30 mL bottles of TW 36 mg PG unflavored that I had stored unopened and still sealed in my freezer for well over a year. Initially this juice is pretty clean, only a bit of nic taste (pepper, slight popcorn to me). After a year at very cold temps this juice was clearly now a tobacco juice. All the "trace" tobacco compounds that come along for the ride from extraction in the typical Chinese juice style had really, as in a LOT, bloomed. I gave away about 150 mL of it, since I can't do all-PG (all my DIYs are VG), but I was a bit broken hearted, as it tasted SO GOOD!!
So I am betting that the Dekang unflavored juices will do the same thing, since they are Chinese and also have a similar yellow to them. IF anyone has any TW 36 mg unflavored, it will list the other compounds in it. What they become I do not know, but the flavor really changed a lot.
I have found that a few of my flavors need a bit of time. Chocolates seem to open up the most with a few days. But then their flavor tends to die over several weeks. Makes sense to an extent, more taste means flavor compounds are exiting their solvent bindings. In fact, most of the flavored juices I make fade after a couple months, at least at room temp.