Thanks for the input folks but I don't think it is amagnet problem. Seems the top tab hits the on/off switch on top of phone.
Here is the holster I have. I monitored it yesterday and it seemed to work better in terms of battery life. I guess the phone auto-offs fairly quickly and maybe I didn't move around that much yesterdy. I don't know. But it just seems a poor deisgn for that part of the holster to hit right over one end of the on/off switch... I called seidio yesterday but did not get a call back... otherwise I like their stuff... and it does resolve the vibration problem I had with the slide in hipt cases. Those deaden the vibration too much and I miss calls and such...