Cisco 3750 - two ports stopped passing traffic

I have a 3750 switch - two member stack - that has been up for four years.  It runs C3750-ADVIPSERVICESK9-M, Version 12.2(46)SE.  It's run flawlessly until the last few weeks.  Interface Gi1/0/6 stopped sending/receiving traffic although it was in up/up mode.  I tried to admin down/up the int but no good.  So I moved the cable to another interface (say 1/30) and the traffic flowed again.  Over the weekend interface Gi1/0/5 had the same symptom.  The host connected to it - a Cisco UCM stopped responding to ping or anything else although the port was up/up.  There were no errors visible when I tried "show log" and no incrementing errors on the interface, nothing in syslog.  I could even see the bps in and out appear to show some traffic.  But from a ping or TCP standpoint the interface was passing no traffic.  I bounced the UCM and still no traffic flowed.  I moved the cable to interface Gi 1/0/15 and now traffic was flowing again.  

I wanted to get some thoughts on here before opening a TAC case.  Does this sound like a memory leak bug with this version of IOS?  A failing ASIC?  Other thoughts on troubleshooting or possible explanation?  Thank you.