The requests are to /.well-known/apple-app-site-association , on several domains.
Reason seems to be an iOS update, documented on
https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/Handoff/AdoptingHandoff/AdoptingHandoff.html#//apple_ref/doc/uid/TP40014338-CH2-SW10.
See also: T111829