Zeta, any number of things can cause numbness after surgery, besides the actual trauma. The presence of a continuous suture could even do it, and it may go away when the suture does (whether it dissolves or has to be removed). I don't think I'd start to worry about permanent numbness until the incision has healed well...if it's still there after a few weeks, then it may continue.
The continuous (so-called mattress) suture is used often because it causes fewer openings in the surface skin or mucus, fewer knots (which cause lumps or bumps), and a smoother incision line.