Kv & new line (\n) errors

So ran into this problem that is flooding the logs. Doesn't seem to affect functionality & actual indexing. Just 80gb of logstash logs a day.

{:timestamp=>"2016-05-26T14:17:13.352000-0700", :message=>"Failed action. ", :status=>400, :action=>["index", {:_id=>nil, ....[super long snip].... "status"=>400, "error"=>{"type"=>"mapper_parsing_exception", "reason"=>"failed to parse [s2_tm]", "caused_by"=>{"type"=>"illegal_argument_exception", "reason"=>"Invalid format: \"2016-05-26T14:17:13.237-0700\n\" is malformed at \"\n\""}}}}, :level=>:warn}

The way I get the KV's is:

kv { source => "TOKEN_VARS" field_split => "!" }

It just so happens that it's at the end of the log line, and it picks up the \n break. I tried gsub on TOKEN_VARS & trim in kv with no luck on getting rid of it.