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.
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.