Well, I'd say it was really only one thumb. She has six digits on that "hand": four fingerlike claws, the "thumb" you see sticking up (it's really only one, though it looks bigger), plus a hidden sixth claw that's nestled deep in the internal corner between the thumb and first finger. So only the one thumb is up.

The sixth claw is kinda hidden, vaguely somewhat like my lame ASCII drawing below:

    ` ` ` `         <-- Four "fingers"
    | | | |  
    | | | |'        <-- Hidden claw (retractable too!)
    (     /----'    <-- Single "thumb"
     |   |
     |   |

I wish I could get a pic of her with both thumbs up! That'd be awesome!

=^..^=

Though you do get two thumbs up, 'cause you get one from Mira and one from me. :)