Have you beeen married more than 2yrs now? If yes, then it's normal, but if not,I would advise notify them . With the current immigration tension in this country, you don't want to make yourself standout.So to avoid the uncertainty,write and tell them.you still get all the benefit of PR anyway.
Also, make sure that you notify them in writing, because down day road in the future,something happens and they dig up your background and file, they would say, that you never filed to remove condition on your card, and therefore you are automatically deportable especially as you said, they stamped a CPR in your passport initially.
Knowing INS, they can come up with any flimsy excuse to make your life miserable if they intent of deporting you for any reason, even if it's their fault.
Also when you write them, whether they make the change or not is then up to them, just keep a copy of the note and delivery confirmation for future reference.
Just my advise.