help ID'ing an off taste?

I brewed a chocolate stout in June and - neglected it for the most part until September, when I finally bottled it. The airlock never went dry, and the temp never went over 75ish... mostly around 70. But It sat there way too long.

So I bottled it anyway at the beginning of the month.

Now, a month later, I poured a couple. the head is perfect, the color is dead on -and the first taste is great. The AFTERtaste however, is very strong coppery/rusty/bloody flavor type - rendering it almost undrinkable.

Since it's already bottled, and I dont' need the bottles, I'll let it sit and see if it mellows. Some of my best beers tasted awful. Just looking for some thought on what might have happened if anyone can Id.

thanks
_TOm

The answer to your question (and many more are...) is here: http://www.winning-homebrew.com/off-flavors.html