epmp session dropping

I just deployed a single 2.4Ghz ePMP 1000 sector (on CMM3) and we only have 1 SM on the AP about .5 miles that is randomly reporting session drops.  RSSI, SNR, and modulation look nearly perfect.  Edetect doesn't report issues with any stray interference and I've moved frequencies around and changed channel width to 10mhz.  The connection is near-line-of-sight and I expect some retransmission and maybe some more packet errors but did not expect session drops.  Error logs report no problems. Running newest 2.3.4 software.

Question: What constitutes a dropped session with ePMP?  I've read over the optimization guide and the only thing I have not tried is moving the Management Packet Rate to MCS0.  Also, it doesn't appear to drop when SM is "active" -at least not that I've seen.  PRTG may or may not show anything that would look like dropped session.  I'm hesitant to deploy more SM's until I get more info on this.  Thanks for any help.  

Spectrum Analyzer ? both side. Attach hee the result

Sorry.  The channel was as clean as 2.4Ghz gets but I finally resolved this issue.  I realized that this SM was on the edge of a 120 degree sector but also I was unclear on the transmit power on the AP.  I found out that I was underpowering the AP by 4dBm and when I turned up the power I had no more session drops.  I've never deployed 2.4Ghz AP's before and the 5Ghz epmp radios will actually tell you the maximum power limit to guide you.  Pretty dumb on my part.  Just wanted to update the post. Thanks.