Should there be concern with a platelet count of 535?

Follow it. I am going to assume that you are not iron deficient, even without being anemic. In the absence of any other indicator of ill-health, the worst thing that this could be is very early essential thrombocythemia. Today this is a usually minor nuisance and seldom detracts from the quality or length of life. You may eventually get a genetic test to be sure, but even so, it may be best left alone 4 now.