Yes this is completely normal. Although the LightWEightForwarder may not be indexing any of your data, it does use the index structure to keep track of the files it is monitoring and forwarding to your indexer
Guys, I suppose this process is running to optimize Splunk service database called fishbucket. Don't you think so? This database is used by splunk even when LWF is enabled. Is there anybody from Splunk support or Splunk guru's to prove this statement?
However this version is the same as the answer above I suppose, I've just pointed to a concrete database name.