There are a lot of known issues/problems in general with using the old Server Protocol HTTP/1.0 – Server Protocol HTTP/1.0 was phased out in 1999 and the new Server Protocol is now HTTP/1.1 starting in 1999. There are also known issues/problems with using Server Protocol HTTP/1.0 with an Nginx Reverse Proxy. My point is simply that everything nowadays should be using the new Server Protocol HTTP/1.1 to avoid any possible issues or problems. Hackers and Spammers use the old Server Protocol HTTP/1.0 because it allows them to do some shady/nasty things that they cannot do with the new Server Protocol HTTP/1.1.
Anyway sounds like my original hunch was correct and besides to avoid a lot of other common problems you want to be using the current new standard Server Protocol so that other strange/odd problems do not occur. You have solved the issue/problem so no you do not need to do anything else.
Great Job!