Teeth should not be sensitive to a point that it alters your behavior in some manner. If you notice any pain that is new, and this pain seems to be getting worse, contact your dentist or endodontist to check things out -- you may have a problem.
Any severe toothache even lasting a day or so that then goes away may signify that the pulpal tissue has become infected, or for that fact, has died. A root canal may be required at a later date -- sometimes even years after that episode.
It is important to note that early diagnosis and early treatment may not prevent a root canal, but it may ensure a higher success rate once root canal treatment is performed and may also avoid you from having an emergency root canal procedure performed in an inopportune and totally unexpected or unwanted time. Control the situation!