Aren't they suppose to stitch, drain hole from the Tummy Tuck after they pull it out of the body?

Your darin stitch is NOT supposed to be stitched, and if the drainage stops it should close up within 24-48 hours, and be healed within a week. The final scar will take at least a year to look the way it will look long term. 

We do not stitch the drain holes closed because that would actually increase your chance of infection.  The heal by secondary intention in about 4-5 days