There will be maintenance tonight, according to a post by Pex:

• Station Cash has an update planned for 9pm Pacific, which should last an hour
• The game has a 90 minute downtime planned for sometime between 9pm and midnight.

Pex warns to pay attention to those server notices!  "If you wait for the server to come offline instead of exiting the game, you may lose recent levels, stars, items, etc because your character not not be saved properly."

Plan accordingly!