An odd one for sure. I believe he looks younger than he actually is, but remember, we are now in December and bucks have lost a lot of weight. Looks like you are up on the KY line, so the primary rut should be well over.
Not sure if folks ever look at their faces on tough pics like these, but I do and sometimes you can get somewhat of a better indication of age. Call me crazy. His nose is long and pointed, which typically indicates a younger deer (more like a 2.5). I do not see the big roman nose on him.
All things considered, I'd go with 3.5. Either way, he will continue to grow those tall tines in future years and be an impressive deer.