Answer: The tree may not be Redhaven as it was advertised or the scion may have died back and it is the seedling rootstock that has grown to be the above ground growing portion of the tree. Let me explain…
When a peach tree is purchased bare root from a commercial nursery or in a pot from the local box store, it is actually a compound tree made up of two genetically different parts. The bottom/underground part of the tree is typically a seedling rootstock that has been chosen because it imparts good characteristics to the tree (i.e., resistant to nematodes, tolerant to drought, vigorous, etc.). If grown to a fruit bearing stage by itself, it will bear small, inedible fruit that you would never consider eating. The top/aboveground part of the tree is typically a desirable scion cultivar that has been grafted on top of the seedling rootstock in the nursery (i.e., Redhaven).
The scion cultivar is known to produce good quality fruit for eating that is harvested in a predictable timeframe. The scion cultivar has its own specific traits that can be recognized and these are different from the seedling rootstock [i.e., presence or absence of leaf glands (and type of glands), type, color and timing of bloom, fruit attributes, harvest timing, etc.]. For commercial scion cultivars, these distinguishing traits are documented by the breeder and included either in the patent or cultivar release information associated with it. Unfortunately, in the commercial nursery industry, sometimes accidents occur where grafted trees are mislabeled where what ends up being sold is not exactly what has been labeled.
Further, it is possible that if trees are grown further along in a pot before they are sold, the scion may die and the rootstock begins to grow shoots and what is in the pot is a healthy peach tree but the "Redhaven" part no longer lives. This could also happen after the tree is planted where the scion dies and new shoots come up from the rootstock and they become the new tree. In either of these scenarios, the peach tree is actually the seedling rootstock only. I have seen this in the field before. Usually some detective work can confirm if this is the case.