Did you get it in writing? If not, I'd be careful. Too often, asking someone in person or on the phone will get you different answers depending on who you're talking to on what day. Sorry, got burned by a share exercise issue years ago when after going into Revenue specifically to ask if I had to pay tax and being told (and, as an innocent young thing believing) that the company would send the details to Revenue and I didn't need to do anything, I ended up SIX years later getting a very large bill from Revenue. Entirely my own fault for not having a clue but have never forgotten it.
Re the requirement to file tax returns every year once you've done it once, if you revert to having only your PAYE income and nothing else you can let Revenue know and they'll stop asking.