M.R.
I think this is very normal. My daughter is almost two, and we joke about her "tracer foods". Those foods we know she had at daycare that we get a "report" on later. Our only concern has been that some of the harsher foods sometimes give her diaper rash (black beans, etc.), but keep up the healthy well rounded diet. If he isn't fussy, the foods probably aren't bothering his digestive tract.