He also makes the point of telling Ellen Page that you never see a dream from it's begining, you simply drop into the middle of it. This is shown nicely in the movie he recalls being on the plane, his landing, going through security, driving home, and then entering his home. He's not simply dropped into being home with the kids.
The jump would be from limbo to the plane. Cobb also seemed to be referring to the start of the dream. Everything we saw within the dreams appeared to have people moving around like normal.
And that's the really cool thing about Inception: so much of the movie lends itself to various interpretations. I believe the narrative and Cobb's story ark demand the ending be reality (notice how he never spends time in his dreams with his children, only Mal) but a person can believe whatever they like.