You are running the stock intake, correct?
I would say that you probably have an intake tract leak. This lets in unmetered air that causes the car to go lean and therefore A/F Learning 1 increases to compensate (in this case +10% is extreme). Your best bet is to get a pressure or smoke test of the intake tract done. This can be done by various shops (although I would try to stick to a Subaru performance shop). If you have an air compressor, you can also build your own pressure test rig (search for DIY pressure test here on Nasioc).
If you find a leak and fix it, then reset your car's ECU via the function found in the troubleshooting menu of the Accessport. Then do additional data logging to confirm. A/F Learning 1 is actually determined from 4 stored values that are determined/applied based on different airflow ranges -> A/F Learning 1 A,B,C,D. You can view all these at once by simply logging them or viewing via live data (so you won't have to actually drive to hit all 4 ranges).