OSD PKI Issues When Initiated from Software Center

I'm having a weird issue when initiating OSD from the Configuration Manager Client.  It works fine from PXE and boot media, but fails from the Software Center.  After the system reboots into WinPE, the install fails on the applying OS step and the following is logged in the smsts.log:

[TSMESSAGING] AsyncCallback(): WINHTTP_CALLBACK_STATUS_SECURE_FAILURE Encountered    TSManager    12/3/2013 3:49:20 PM    1116 (0x045C)
[TSMESSAGING]                : dwStatusInformationLength is 4
    TSManager    12/3/2013 3:49:20 PM    1116 (0x045C)
[TSMESSAGING]                : *lpvStatusInformation is 0x8
    TSManager    12/3/2013 3:49:20 PM    1116 (0x045C)
[TSMESSAGING]            : WINHTTP_CALLBACK_STATUS_FLAG_INVALID_CA is set
    TSManager    12/3/2013 3:49:20 PM    1116 (0x045C)
[TSMESSAGING] AsyncCallback(): -----------------------------------------------------------------    TSManager    12/3/2013 3:49:20 PM    1116 (0x045C)
Error. Received 0x80072f8f from WinHttpSendRequest.    TSManager    12/3/2013 3:49:20 PM    1116 (0x045C)
hr, HRESULT=80072f8f (e:\nts_sccm_release\sms\framework\osdmessaging\libsmsmessaging.cpp,8919)    TSManager    12/3/2013 3:49:20 PM    1116 (0x045C)
sending with winhttp failed; 80072f8f    TSManager    12/3/2013 3:49:20 PM    1116 (0x045C)

I am using SCCM 2012 R2 in native mode.  The error sounds like it doesn't trust my PKI.  However, I'm perplexed b/c this isn't a problem with PXE or boot media.  Do I need to import my CA into the WinPE image?  Any help would be appreciated.