I think that there should be a notification when your colony passes the threshold to start drawing expeditions for a certain commodity. A pop-up along the lines of "you receive an incoming transmission from a hegemony commissary: We have taken note of your increased (commodity) production. Your actions are threatening the economic security of the hegemony and its citizens. If you do not cease or reduce operations by (date), we will have no choice but to reduce them ourselves."
A bit of flavor and also help for inexperienced players to know that they are in danger.
Also, I've really enjoyed how nexerelin has pop up notifications for major events (particularly for faction wars and stuff that requires a response). I think implementing some of that for major events could avoid situations where the player misses notifications in the scrolling list on the side of the screen. There's a lot there and it's easy to miss stuff, and missing expeditions notifications is a pretty big deal. It would be particularly nice for AI inspections where you have a choice of how to respond. Perhaps you could laos have the choice of allowing the hegemony to reduce production by one of your industries for a period of time instead of trying to fight off the expedition.