Issue - 400 Errors in WPT but not in chrome timeline

We moved our static assets over to a s3 server to save on costs. And now when I run a WPT i’m getting a lot of 400 errors from the s3 server. However, when I look in my chrome timeline I’m not seeing the same errors.

Here’s a result.
https://www.webpagetest.org/result/170324_ND_1174b7759851b0c6b4395447d6ff5ab2/