AFAIK airlines impose their own conditions on passport validity dates, because they're on the hook to remove you from the country they've brought you to, if you get refused entry - costs them the return flight. I don't know what visa requirements there are for the Philippines
but if you already had a valid visa, you should have been good to go. A lot of countries only need your passport to be valid on entry, and it doesn't matter if it expires while you are there. Why should it? You don't need a passport to return to your own country; it just makes it easier.