awesome, thank you for you prompt reply. these logs weren't going into the default logstash-* indices, they are going into nginx-* indices, so indeed i've created a template which i reference in the elasticsearch output. I wasn't aware of the default template helping out behind the scenes for logstash-* indices. thanks!
so i am trying to reindex the glob of nginx-YYYY.MM.DD indices, Reindexing glob of indices