I think it means that you have been out on your mission a year and like a camel that stores important nutrients in it's hump you have stored important learning experiences in your book of life like: testimony, love for God the Father and Jesus, an understanding of the plan of salvation, love for the Church, and love for home and family. I can't believe how much I miss Jordan some days. He still has to fill up another hump (year 2009) but if times keeps going as fast as the past year, he'll be home in a flash.
It is a great blessing to have a missionary.