Retrieving profile doesn't return accurate profile soon after updating

I’m running into a problem as follows:
Time 0: I add a note to a customer using the Rest API
Time 1 (very shortly after Time 0): I retrieve the customer using the Rest API
The customer returned to me will include all the notes except for the note added at Time 0.
Time 2: I retrieve the customer again using the Rest API
The customer returned to me will include all the notes including the note added at Time 0.

Any idea how to fix this?

REST operations are not assumed to be atomic; caching and delay in database operations may produce the result you are seeing. I would recommend that you just update your local model, then persist it via the API, rather than relying on a returned model to include the updates in short order.