Possible failed peanut challenge

My son was 9 months old when tested for food allergies. I was breast feeding and he had horrible eczema. Peanuts came up postivie VIA skin and RAST. At age 21 months he was negative, not sure if it was VIA Rast or skin, I dont remember. I do know though, that is was only one test done.
He had a food challenge and broke out in full body hives. This was his 1st exposure to peanuts.

The second was at age 3. He was in Sunday school and they made bird feeders using peanut butter. About an hour later his nose was running like a faucet, he couldnt stop sneezing and he had some hives on his face.

Now, at age 6. he tested negative via rast and skin. We went for a food challenge last week and an hour into the test, and about 2tsp peanut butter his eyes got itchy and swelled up.

NOW, he has seasonal allergies that DO give him itchy eyes, but NEVER NEVER NEVER swollen eyes. His allergist said he was surprised. For one, he ate quite a bit of PB, and 2, both tests were negative. He is thinking it could have been a seasonal allergy reaction and said we can re-try the challenge in the winter. I am skeptical, what do you all think?