No, it's the caching behaviour of the default website page. This is a well-known issue (though why anybody would want to open their website in a browser before they've put anything up baffles me).
The redirect to the default page shows that the site's subdomain is being resolved correctly (that page is generated by the system when the user's home directory exists but public_html has no non-default content); a local DNS problem would point to a "domain does not exist" page. The default web page is must-cache, and while it is easy to clear your own browser's cache (or open a different browser), it is often cached by the ISP as well (many static pages and resources are in order to improve apparent performance), and when that happens there is no choice but to wait for the page to "age out" (usually 6-24 hours).