A reader tipped us off that it looks like the Four Seasons Seattle is undergoing some repair work already:
From my office I noticed that the Four Seasons is replacing the glass on all of it balconies/terraces. Looks like every balcony on all of the apartment floors and the common area at the top. You can see from the photo. All glass panes have been removed and the replacements are stacked on each balcony.
Probably as simple as a fault in the original glass supplied. Looks expensive. Wonder what happened and if there are implications for other structures with glass.
Seeing as the Four Seasons was built in 2008 this may be warranty work as the building approaches its four year anniversary / statue of limitations on developer warranty.