Funny you should ask. It's either Jeff Laubenstein or Christopher Moeller - I just met them both at a gaming convention a few weeks ago, and one or the other mentioned they'd done those counters, but I cannot remember which one it was, and they're both credited in the 4th ed. rulebook.
My inclination is to say it was Chris Moeller, since he's credited among those who did "Color Illustrations," and the look of the counters seems to better match the style of 'Mechs on CCG cards he did at about that time, than they match Jeff's work.
We're in touch with both of them again, so next time there's an appropriate chance, I'll ask them.
