The Eberron Campaign Setting on Random Starting Ages (27) lists a warforged's random starting age as 0 then +1d12 if its first class level is in a simple class like barbarian, +1d6 years if its first class level is in a moderate class like bard, and +1d4 years if its first class level is in a complex class like wizard.
This is the exact opposite of how random starting ages are determined for other races: they enter play older the more complicated their first class. This(This seeming weirdness goes unmentioned by the Eberron Campaign Setting errata.)
Was an official explanation ever offered for warforged starting ages? That is, did a designer ever mentionsay, for example, that because of, like, a warforged's magical-mechanical brain, a warforged takes longer to learn how to act on instinct than to learn how to perform complicated intellectual tasks?