hope u dont!
keep water perfect and add some supplements to the feeding and hopefully they wont get it...if u added water form his tanks....ull prolly se it come up...thats why the only water that should ever go into ur tank is new clean saltwater....if u didnt however corals dont tend to bring ich with them...but there is always a bit of water transfer.
You know, there's always a certain number of parasites living in our systems. When a heater fails or some other condition stresses our fish, we see an outbreak even though we didn't do anything that would introduce a new population of parasites into the tank.
If your fish are thriving in a healthy system I don't believe you have a thing to worry about.