Quick loss of flavor in wit - ideas?

I brewed up a wit at the end of November, and bottled it mid-January. Longer in the fermenter than I would have liked, but I was slacking. No issues at all, though. When I bottled it there was a fantastic haze, color, aroma, and flavor. Real bold coriander and citrus... quite refreshing.

However, I just popped open a few bottles over the last couple of days, and there's practically no detectable coriander or citrus goodness; it's rather bland. Just two weeks ago this beer had great flavors and aromas. It seems like they disappeared very quickly. Would there be any particular reason for this? How could I, in a future batch, keep the flavor and aroma longer without making it too overpowering at first? I've had a few aged wits, and they still retained their "wit"iness.


Here's the recipe I used:

Batch Size: 5 gal
OG: 1.043
FG: 1.009
Mash: 154 degrees F for one hour
Fermented at 63 degrees F with WLP400

Malt Bill(rounded):
Wheat Malt 41%
Pilsner Malt 31%
Flaked Wheat 25%
Acidulated 3%
Half a pound of rice hulls to help with the sparge.

Boil:
3.8 AAU Hallertauer at 60min
1oz ground coriander at 2min
1oz fresh citrus peel (valencia orange and white grapefruit) at 2min

I would guess this is due to oxygen contamination. Your beer was doing just fine while it was waiting patiently to be bottled. Then when you bottled you got a little air in there and it has gone stale.