Database event_id not recorded in states table on version .40

Not sure if this is by design or a bug. I was running 0.39 for a while and happy with it in general. I upgrade to .40 when it came out and noticed my enter/leave home events not always being triggered so I downgraded to .39 again. What I noticed in the database however was that during the .40 install the event_id field was not being populated in the states table.

Have not seen any issue in history page so not sure its a problem but wanted to make sure its not going to create problems later on if it is a bug. There is no longer a clear link between the states table and the events table.