Bad Turkey Experience

Decided to cook the turkey on the Green Egg vice oven this year. I placed the drip pan on the place setter. The turkey was on a V rack breast up. V rack was placed directly on top of drip pan. Top of the breast was about 2 inches from the top vent. I cooked the turkey at 350 degrees for 4 hours (13lb turkey). I cooked it just like it said for "The Perfect Turkey" on the Big Green Egg home page with celery, onion and chicken broth in the drip pan. After I got the turkey off the Egg I let it sit for about 20 min. Temp. in the leg was 180 degrees. I took some dark meat off the leg and it was the best dark turkey meat I have ever eaten. I was getting very excited about how the breast meat would taste. As I carved the breast I noticed that it didn't appear to be done. The side of the breast was done but the deeper I carved the more slimy the meat got. I was able to carve off enough cooked meat for everyone to have one serving but had to put the meat back in the electric oven. After cooking the meat for another hour the meat was done but ruined because I had carved up both breasts before putting them back in the oven.

The only thing I can think of was the breast was too near the top of the vent an maybe the air was not 350 degrees as it exited the egg. Do any of you experts have an idea of what I did wrong?