Between approximately 10:28 PM 15 May and 4:58 AM 16 May US Pacific time, updates to our tag system on our US site were delayed more than one hour. Customers may have noticed that device information was not updated as quickly as usual when retrieved, and messages targeting tags may have not included devices/named users where those tags had recently been added. Similarly, messages may have been delivered to devices/named users where tags were recently removed. No other systems were impacted. This was due to an unexpected burst in traffic, which was mitigated. Our engineering team is also improving the underlying system so that similar traffic spikes of this shape will be handled more efficiently, avoiding delays. We apologize for any inconvenience.