Really well phrased here... I'm in agreement with you that this is pretty unusual.  I personally do not quite understand why we're seeing this degree of warmth just as an El Nino is taking off (and not after it maximizes, which is the expectation).  By the way, it's my experience that above-average tropical Atlantic SSTs tends to put a damper on El Nino development, so again, this combination is odd.  Time will tell with this El Nino...