The file manager makes a new request for each image displayed. If you have over 200 images, then you get 200 requests. I think the only reason the requests were coming back as "bad" is because after the first few the remaining were blocked and then returned bad requests for the rest. I don't think the actual requests were bad without the block.
If they have an error log showing the bad requests then I could verify my claims. They should be able to get that for you, but if the issue is resolved then we can probably just let it be.