No it's not. Congress is one of the parties; it is the entity empowered to act on behalf of the people of the United States in the matter of copyrights. If the holders of copyrights come to it and petition it for an extension, and it agrees, then that is a mutually agreed decision by both parties to the agreement.
If what you're really getting at is that your elected representatives did not represent you in this particular case, well, that happens every day on a lot of things. I used to live in California, where I had Boxer and Feinstein for Senators; they didn't represent me for squat. I got out-voted.