If you are using Hootsuite or Tweetdeck, you will not see all of your tweets that have been retweeted in Twitter. Some of them are hidden in the web application of Twitter. That makes me a little cranky.
If someone is using the web application of Twitter and uses that Retweet button they have there, you will not see it in your mentions area of Hootsuite and Tweetdeck. So you should go into the web application every once in awhile to check if you have any retweets there. There is a Retweets link right below the Favorites link on your home page. Watch the video for more info on that.