I'm using the kolide launcher for osquery and whenever I install the package onto a Windows host, the application log gets spammed with Event log 1,

caller=level.go:63 level=info caller=log.go:69 component=osquery level=stderr msg="...

messages, has anyone else seen this issue?

As answered on #kolide osquery is sending a message to stderr, and launcher is passing it along. That log line is truncated. You can get the full one with

Get-EventLog -LogName Application -Source "launcher" -Newest 30 | select -ExpandProperty message

Please stick to one place for questions.