There being an imminent danger for the Faith, prelates must be questioned, even publicly, by their subjects. Thus, St. Paul, who was a subject of St. Peter, questioned him publicly on account of an imminent danger of scandal in a matter of Faith. And, as the Glossa of St. Augustine puts it (Ad Galatas 2.14), 'St. Peter himself gave the example to those who govern so that if sometimes they stray from the right way, they will not reject a correction as unworthy even if it comes from their subjects.” (Summa Theologiae, IIa IIae, Q. 33, A. 4)
And from the online Douay-Rheims Bible + Challoner Notes this entry from Galations, Chapter 2 (bold emphasis mine):
At the end of the day, we’re still Catholics. That makes us family. In other words, it ain’t over ’til it’s over; so with that in mind I’m offering a bit of fraternal correction."