I took the liberty to re-format your post a little using https://jsonlint.com/
to make it more readable.
To answer your question: using http://geojson.io
, I can see the point you query with lies outside of
document 4, but right on the edge of document 41. So this was probably a bug that was fixed in after 1.7.
"_id" : "4"
"_id" : "41"