The RSS feed for this blog has been a bit wonky in Safari for a while. Specifically Safari would randomly pick dates for posts, randomly showing old posts as new ones. I think the problem was I was missing a timestamp on each item. This was as simple as adding in:
def item_pubdate(self, obj): return obj.timestamp
...on to my feeds class. Apologies if this has been messing your feed. Safari and Shrook now seem much happier.