As I understand the ick life cycle, the little buggers munch flesh, multiply, then drop cysts off the fish, which sit in the sand or rock or wherever they land for about a week or two, and then they climb back on your fish and start munching again.
So any object taken out of a tank with an active outbreak will expose your fish to ich. Healthy fish can ward off a little ick attack and won't get sick, but if fish are stressed, or otherwise susceptible, they'll come down with an infection. Hippos seem to be particularly prone to ick. When I had one, he got sick while none of the other fish ever showed any signs of illness. I would feed garlic, and just watch, but in a day or two if it's getting worse, I would immediately treat your tank with Kick Ich. It's a totally reef safe treatment, and it will kill all the ich cysts and adults. I used it with total success and no damage to corals, fish or inverts.
Nate