Just got an email from them:
------------------------------
Dear Kindle Customer,
We are pleased to let you know about some improvements that we made to Kindle book samples:
- Samples that you download from the Kindle book store will now be saved in the cloud so that you can access and read them on any supported Amazon device or Kindle reading app.
- You can delete your samples from the cloud on any supported devices or Kindle reading apps, or from Manage Your Content and Devices. (
http://www.amazon.com/mycd ).
Amazon devices and free Kindle reading apps that support these sample improvements are: Fire HDX, Fire HD, Kindle Fire HDX, Kindle Fire HD (2nd Generation), Kindle Voyage, Kindle Paperwhite (2nd Generation), Kindle (7th Generation), Fire phone, Kindle for iPhone, iPad, and iPod touch version 4.5 or greater, and Kindle for Android version 4.7 or greater.
To learn more about these improvements, visit our help page:
https://www.amazon.com/help/kindle/samples
Thank you for choosing Kindle.
Sincerely,
Amazon Kindle Support