Ruy Diaz, were you aware that you were being recorded as it was happening? If so, your voice may have deepened "on its own" (i.e., without you doing it intentionally) as a way to project masculinity, command, etc.  
 
This happens all the time when dudes call chicks on the phone, or strike up conversations with them in public. Their voices drop a bit so as to project masculinity. (Ludacris has a joke about this on one of his comedy-sketch tunes). 
 
Also I would note, and don't take this the wrong way, that in Hispanic cultures this effect is even more highly pronounced. Ever listen to those audio-tapes they make you listen to while learning Spanish? Where the speaker says a line in English, then in Spanish? The line in Spanish is invariably noticeably deeper. If you hear "Where is the train station?", the next line, "Donde esta la estacion de tren", spoken by the exact same guy, will be much, much deeper. 
 
If your voice were recorded without you being aware of it, AND it was deeper, I'd be very suprised. 
 
Peace.

Most people are suprised to learn that their voice sounds slightly higher-pitched to others than it does to themseleves. This is because your own eardrums catch vocalizations that go through the body (skull) as well as bouncing off walls and back into your ear, and the denser medium has the effect of lowering the pitch slightly. (Imagine hearing someone talk underwater, that lowers their voice considerably - in addition to obscuring the crispness of the sounds, etc.) 
 
Those who have recorded their own voice, singing, comediens, etc., are very familiar with this effect. Once you've heard your own voice on tape a few times, it ceases to sound "weird". It can even sound "normal" after a while. 
 
I think my in-the-air voice is fine. A little higher than I'm used to, but fine.