But yet, parent poster's phone dropped, so that migration from UTC=GPS+N to UTC=GPS+N+1 would result in the same conniptions we all have to deal with an extra second in the day. Even if it is at the phone's presentation layer, that's several GB of software that might hold lurking N+1 bugs causing the data layer to drop.
Agreed, while the CDMA specification requires tight time syncing, like everything else the UNIX OSs used to run the equipment can receive the leap indicator. Any problem within the OS, or the software reading date/time from the OS can cause instability.
Also, without knowing more about what exactly went wrong with your phone, it's possible other infrastructure within the network was unstable, signalling equipment, etc. I can't remember exactly, but I think some of the CDMA equipment at my previous company had a leap second problem previously. And the equipment is no longer being maintained or patched really.
Past life $work made UTDOA equipment for GSM networks. The hardware used a number of GPS modules from various vendors to obtain GPS time, which someone noted above includes leap offset broadcast in the periodic almanac.
Anyway, of three different module vendors, two got leap handling wrong. Then our own code had its own leap bugs, on top of the OS (Solaris) timekeeping bugs such as clock jumps and timezone update issues. Good times.
