how lean is lean???

[j.fro]

After a dyno test, the dyno operator said my car was running lean. the graph showed the air-fuel ratio half way between 14 and 15:1 throughout the dyno pull. I've read that 14.7:1 is ideal, which is about where my numbers were, but I've also read that under full throttle, it should be around 12 or 13:1.
Am I really that lean??
BTW, it was a Dynojet, and my RW HP was 224.73
2000 Box S with headers, no cats, and an EVO intake system w/ a dryflo air filter.
128,000 miles