So I heard back from PagerDuty;
"Thank you for bringing this to our attention. Unfortunately, it looks like, due to the nature of Windows-path names, SolarWinds is sending out invalid JSON (verified here:http://jsonlint.com/), which contains unescaped "\" characters, to our integration API. "
So I guess what we have here is a case of Solarwinds and PagerDuty standing and pointing fingers at each other?