The Reporting interface allows you to use time filtering to view a specific date range for a campaign. This time filter includes setting a day and time you want to start at. It is possible, in some cases, that your send number will be higher than your queued number depending on when you set your time filter start time.
For example, if your filter start time is set at 12:00 AM, you may have had 10 messages sent and 9 queued because the 10th sent message was queued before 12:00 AM. Adjust your filter start time to be slightly earlier to see the correct number of sent and queued messages.