marvel cinematic universe - Why was the removal of the shrapnel just "thrown-in" at the end?

The idea is that Iron Man 3 closes a major chapter, or set of chapters, of Tony Starks life. This chapter started when he was first taken hostage and the shrapnel was embedded in his body.

One of the themes of this movie is dependence. Tony has been dependent on the suit, on the reactor in his chest, for a long time. After all of the events in IM1, 2, Avengers, and IM3, Tony has finally learned that he's no longer dependent on the suits. To show this to Pepper he destroyed all of the suits he created. He also finally had the peace of mind to remove the shrapnel, the one thing that made him dependent on the core in his chest.