In the past, Starwood has allowed instant points transfers within “households.” In other words, people with the same address on file with Starwood could transfer points freely. This is of course intended for family members, though was often taken advantage of through “temporary” address changes so that points could be transferred. Well, according to this FlyerTalk thread, as of November 15 household transfers are no longer instant. Apparently these requests now go through a special department that check eligibility, so transfers can take up to five days.
I would expect that they’ll no longer approve transfers for members with different last names that just recently switched their addresses.
I certainly can’t fault Starwood for this, as they’re still quite generous by allowing “legitimate” household transfers.