A few weeks ago we sent out an email regarding changes to our session IDs (they are now longer, up to 255 characters). If you are storing session IDs for re-use, make sure that your database field supports this (we recommend a length of 512 just to be safe).
Also, when you switch your app from staging to production, make sure to also modify the client JavaScript src URL and server-side API URL to point to production! You’ll also want to make sure that you start using production and not staging session IDs.