It's always a good idea to check multiple sources several times for the lowest fares. As much as I like booking buddy, farecast ,and kayak I still check other sources just in case. Farecast does try to predict the trends for you.
May I suggest that if you get one that satisfies you that you don't beat yourself up when one shows up a few days later a bit cheaper. It seems like airfares are as volatile as the stock market these days.