this behavior can have two reasons:
1. You can not rely on the time accuracy of your recorder display. It is not unusual that displays and graphic processing routines introduce a delay.
2. Canon DSLR Cameras are known to have a shift of 1-2 frames between audio and video. If your camera does this, then the resulting Timecode will be also 1-2 frames off because it was recorded on the audio track of your camera. To compensate this there are several ways to do this in the Tentacle Sync Software. Just look out for the Offset parameter of the “Read Audio Timecode Function” or the “Set Audio/Video Shift” Function in the Context Menu.