The problem is pretty simple. The Irish, not unlike plenty of other nationalities, have a bit of a double standard when it comes to what they'll put up with. If an Irish person said that - although phrased as it is, it might be a bit unlikely - there wouldn't be a problem. However, coming from a foreigner, it would/could be seen as derogatory.
We don't really use the term 'paddy' to describe ourselves, although it's not completely unknown. We generally stick to 'Irish'. Remember that we're a well travelled people and because of our diaspora, particularly in the English-speaking world, most people have some knowledge or concept of the Irish. The problem is that this is often riddled with stereotypes and also the more exaggerated forms of cultural expression largely dreamed up by emigrants as a way of keeping up their identity. The point is, we (the native Irish) really don't like being patronised or stereotyped and because this happens to us quite a lot, we are liable to react.
The irony - and again the double standard - is that we'd often tolerate the same observations or humour from one of our own. If you walk around some Irish towns late on a weekend night, you might think there's plenty of justification for the drunken Irish stereotype - but I'd still think twice before commenting on it aloud with a foreign accent if you don't want people to take offence. Whilst I realise your husband is Irish, the point is you'll be regarded as Australian for quite a while, in the same way as I'm sure he's still regarded as Irish over there.
