It's almost certainly a temporary glitch. Delta and VA just applied for a 10-year extension of their joint venture, which includes:
http://australianaviation.com.au/201...ific-alliance/
coordinate[d] pricing, schedules, routes, offer reciprocal frequent flyer benefits and share revenue under the concept of “metal neutrality”.
So, unless Australia killed their JV and this is the first sign, I can think this is nothing but Delta's famous IT working its magic again.