OCSP requests returning "unauthorised"

One of the possible reasons you might be interested in obtaining OCSP response immediately, is using OCSP stapling mechnism - you obtain OCSP response in advance and include it in TLS session negotiation. This improves privacy of users, as they do not query OCSP server about your certificate directly - which makes CA unable to track who (distinct IP addresses and browsers) is visiting websites protected by their certificates.