Wine tasting question...

Can someone explain to me what caused this?

I am still pretty new to wines. I know I like reds (syrahs probably the most so far) and gerwurtztraminers. So for thanksgiving, I decided to try hold my own wine tasting so I can actually experience/taste the differences in wines. I had one Pinot Noir and two Cabernets. I really enjoyed the Pinot Noir and had a full glass before trying the Cabernets. Once I opened the Cabernets I could actually taste some differences--such as a berry flavor vs. an oaky flavor. But I was not able to taste these distinctions for very long. After about half a glass of each of the two Cabernets, I began having this unpleasant bittery flavor in my mouth that would not go away. It was so bad that I could not taste anything other than this flavor. Would this be the tannins? I seem to remember hearing once that certain wines are "rich" and that you cannot have too much of it--similar to a rich cheescake I guess. Is that what I experienced? :confused:

Thanks for the responses. I am at work so I don't have all the details on the wines with me. But what I do remember is that one of the cabs was a Bogle 2001 or 2002. The other I can't remember for the life of me right now. I let them breathe for probably only 5 minutes or so--we were "thirsty":p . They were both served cold. We drank them after the turkey dinner by probably an hour, so my palate was relatively clean. The Pinot was a Chalone vineyard 2003 or 2004--this was the wine I drank first with no after taste at all. And I don't know if this helps, but when I started getting the after taste from the cabs, my wife noticed that the back of my tongue was very purple--isn't the back the part of the tongue where bitter is experienced? She seemed to say that it looked "coated" as opposed to stained as with otter-pops or lollipops. There may have been a noticeable metallic taste--I know there was another flavor besides bitter--but the bitter was so overwhelming that I just couldn't taste anything else. I will post the third wine tonight. Thanks again!

Wow...thanks everyone for the input. Here are the exact names of the wines. 1) Chalone Vineyard 2004 Pinot Noir; 2) Bogle Cabernet 2002; 3) Gundlach Brundchu 2003 Cabernet.