Not wanting anyone to know after all the problems earlier she wants to keep the news from everyone until she is sure everything will be OK. Karl sees her at the hospital and asks Max if everything is OK with Steph. Max thinks that maybe the cancer has come back and she's keeping it from everyone so as not to worry them. She then realises that she has to tell Max the good news. Got this from the OZ site. Which also says that Izzy and Paul become the Ramsey Street 'neighbours from hell' after they move into Lou's old house which Paul now owns.