Thank you, Harold, that's very helpful! My guess was that such matches would happen at least occasionally, but beyond that I had no idea.
Naturally I'm more drawn to agents who represent illustrators whose work speaks to me, but I didn't know if that was anything that mattered in practical terms, although of course it's some indication of an agent's tastes and sensibilities.
And of course I'd love to hear anything that Jennifer Laughran or anybody else has to say about this.