That is not how you tell the age of a whitetail deer
Turkey Fan, I think he was meaning the white mark was unique to this deer that he had noticed as a spike, then a small 3x3 (6 for you boys) and now a bigger 6 (3x3). That way he knows he is a 3 1/2 year old deer just based on this unique marking.
To the question I'd pass, immature and rack wouldn't warrant a second look from me.