Tongue scraping has indeed been around for centuries. However, there is one caveat I'd like to add. There's a reason that dentists need to know if you're allergic to antibiotics - bacteremia can result from mucking around in the mouth and dislodging oral microflora so that they potentially make it into the bloodstream. The U.S. Center for Disease Control does, in fact, have an article which recounts a case of cardiac complications due to bacteremia which, it posits, might have resulted from tongue scraping.
This isn't to say you shouldn't do it! Not at all. It is a recommendation, however, that before you make any major changes to your oral hygiene routine which might involve scraping or otherwise doing slight violence to your tissues which you haven't done before, you check with a dentist or doctor to see if they have any recommendations or warnings about it.
If you've been doing this regularly, of course, have at it. Note: I am not a doctor. I am not trained in medicine. I offer this advice solely because it is advice I have received from trained medical personnel I trust.