carbonic acid taste lingering?

[ombre42]

Basically I was wondering if the bite from carbonic acid goes away immediately after flattening the beer or does it linger?
I agitated the beer in the glass enough to flatten it and the taste did not improve.
The beer tasted fine two 2 weeks ago, but has a bite now and I'm trying to narrow down the cause and it is overcarbed now. My other suspicious is beer line buildup-I'm new to kegging btw.

 

[Bobby_M]

To rule out the lines, pour 3 ounces into one glass, then pour another 3 ounces into a second glass. Compare the taste. The first pour would be the one with the off flavor.

 

[ombre42]

After de-gassing the beer over a week and getting it to a reasonable level I have found that the "bite" has gone.
I am answering myself. The carbonic bite does not immediately disappear upon flattening, but will with time.