The bottom line is, No, you can't retrieve the request headers using Selenium.
Details
It had been a long time demand from the Selenium users to add the WebDriver methods to read the HTTP status code and headers from a HTTP response. We have discussed about implementing this feature through Selenium at length within the discussion WebDriver lacks HTTP response header and status code methods.
However, Jason Leyba (Selenium contributor) in his comment straightly mentioned:
We will not be adding this feature to the WebDriver API as it falls outside of our current scope (emulating user actions).
Ashley Leyba further added, attempting to make WebDriver the ideal web testing tool will suffer in overall quality as driver.get(url) blocks until the browser has loaded the page and return the response for the final loaded page. So in case of a login redirects, status codes and headers will always end up with a 200 instead of the 302 you're looking for.
Finally, Simon M Stewart (WebDriver creator) in his comment concluded that:
This feature isn't going to happen. The recommended approach is to either extend the HtmlUnitDriver to access the information you require or to make use of an external proxy that exposes this information such as the BrowserMob Proxy