Let me comment on this one myself, since I had to do some research. When a domain gets a hit in our system, we cache the domain details for 5 days. But if the domain gets another hit the cache is changed to expire at midnight.
So in this case, if you have the for sale information set to one url, and the domain hasn't gotten a hit at all the for sale url will be correct when it gets it's first hit. But if the domain gets hits on a normal basis, the url will be correct after the cache is purged which is at midnight.
Hope this makes sense.
Donny