Blocking adjacent seat to elite member?

I remember that United used to block the middle seat next to elite members some time back. Is this benefit back?

Earlier this week I was flying SFO-EWR and on the flight status page, it showed the middle seat next to me as taken. However, when I displayed the seat map on the check-in page, it displayed the seat next to me as available and selectable. Even up until departure the flight status page (as well as at the gate) showed the seat as taken, but yet no one actually sat next to me.

I didn't think that SHARES had the capability to do that, so I wouldn't be surprised if it were some fluke in the system.