Ferritin lab results do not solely show stored iron level. Ferritin is also a phase reactant that responds to levels of inflammation. It can be wildy inaccurate. When I had a severe reaction to an infused cancer drug, my ferritin increased to 2000 for a short period, then resolved right back to normal level.

You are talking about single digit variations here. A change of 7 points. This much change could happen because your higher number was after a meal with something that slightly provoked you immume system, or you have a bad night's sleep, lack of oxygen leading to a little inflammation.