Nah Matt, these aren't really flatworms, they just kinda resemble tiny ones. The only thing in the bag that went into the breeding trap from you was the egg strand, I pulled bryopsis from my "farm" and added yours back to it. I figured it would be better if it was attached to a rock. I don't think there is any way a flatworm could have gotten in to the breeding trap.
PS - Something is fishy with my bank account, it has plenty in it, but it won't accept my elec. payment, your PayPal, or my cable internet payment. Called this AM and they said fraud detection had it "under review"...yikes! As soon as they decide that I am worthy of spending my own money (and that someone else isn't doing it for me) you'll have your transaction. Sorry for the delay...not going to stiff ya'
Jason