My specialty flavors are fading over time

[JasontheBeaver]

I'm not sure this is a kegging/bottling issue but it's where I'm starting to look first.
I first noticed a problem when I made a coconut porter. After it was fully carbed in the keg it was unbelievably good. I nailed the perfect balance of coconut flavor and was so proud. But as the weeks passed the coconut flavor slowly faded to the point where only I could faintly detect the flavor. Strangely it was still a really good porter that everyone loved.
Now I've made a couple Belgian wits using coriander and orange. Again, after carbing, both batches came out of the keg with outstanding flavor and balance. Now after 4-6 weeks they've faded into just decent wits with the coriander only slightly perceptible.
I was thinking my next step will be to brew another batch and bottle a few immediately then wait and see if the bottled beers fade similarly to the kegged beer.
Any suggestions in the meantime?
Or is this a matter of some beers are best fresh and don't age well. Maybe this is why there are no outstandingly good commercial coconut porters?

 

[Yooper]

Spices and hop flavor fade as the beer ages. Oak fades, too. That's just the way it is. Some beers age very well, like barleywine. Some beers do not. The good news is that an overspiced beer can be better in 6 months, or like in a case where I over oaked a beer, it mellowed in 6 months to be perfect!

 

[BBL_Brewer]

Just speculating, but it could be that the flovorings are dropping out while it cold conditions. Bottling next time (at a least a few) should give you a better idea of what to expect. Hopefully someone with some experience will chime in.

 

[JasontheBeaver]

Hmmm, well my first reaction was to consider doing as Yooper hints at, just add more spice. To take it a step further, since I'm really wanting to enter these beers into competitions I guess I need to experiment with the aging process so I can time my entries accordingly. Otherwise by the time my beers are judged they're often already on the downhill side.
The next improvement in my brewing process is water treatment so I'm wondering what effect that will have on longevity other than if it makes a better beer than I'm starting from a better position.