No, I don't think it is, but keep in mind that a lot of things affect your weight...it is not a direct linear function of the calories you take in. You could be retaining water from excess sodium or hormonal fluctuations, or if you've worked out, your muscles may be holding on to water, and those are just a couple examples of things that change from day to day. Stay the course and you will eventually see a drop. That's one reason many of us weigh weekly instead of daily...there are so many fluctuations that it can really drive you nuts! Just make sure you are very, very accurate in your logs so you have an accurate number of calories in.
"If you drop an egg, you don't say, 'Oh, shoot' and drop the other 11, do you?"
-Source unknown, but obviously brilliant
Reached goal 4/16/2010...but kind of afraid to look these days