Zkeg aftertaste

My first brew went perfect, the whole process from start to finish was a dream. My second brew was even smoother up until the last few pints that flowed out of my keg. I noticed a bit of an aftertaste to my brew. I am guessing it is because it was the "bottom of the barrel" and I was getting more sentiment in my glass than before. Is this normal or was my beer beginning to go bad?

Doubt your beer was going 'bad'. Its probably as you suggested, you were sucking up some of the sediment from the bottom of the keg. You gotta figure it is made up of hop residue and yeast particles. To some, that ain't heaven.....

Does the sediment leave a bit of metallic taste, I would think that the left I we hops and such wouldn't be a metal taste and more representative of hops and grains?

I would usually associate that with CO2 bite. When a beer is over carbonated, I can taste a metalic taste. Maybe the last few pints are just over carbonated?

The keg pulls from the bottom so the first pints would have sediment not the last.... unless you moved the keg.

Ahh, but the last pint or so will 'slurp' the sediment up a lot of times. I've had perfectly crystal clear last pints, and chunky ones on the next brew. Heck, at a local watering hole, I've drank the free, last, chunky pint when one of the Stone anniversary ales blew the tap.

I think the over carbonation may be ther culprit, how might I go about making sure the carbonation is where it is supposed to be when I am getting low on brew in the keg? Once it is over carbonated is there a way to reverse it or am I just going to have to live with it for that last few pints. It actually ended up being 3 pints and two bottles to be exact.

Guess it depends on your setup. Ideally your beer should have the same carbonation level the whole time its in the keg. If you have the pressure set to high, then as you drink your beer, it will get progressively more carbed until it hits a certain level. You may be drinking it before most of the keg gets to that higher level. If your setting the regulator pressure to the recommended pressure for the style of beer and leaving it alone, you should be fine through out the keg.