In his commentary to the Talmud, Rashi usually just gives us a simple explanation of the word or phrase he is commenting on. However, every so often he quotes his teachers. It seems to me that when he quotes his teachers he almost always questions their explanation, or outright disagrees.
Is my impression correct that Rashi usually quotes his teachers to disagree with them? Has anyone done a study of all of Rashi's comments to see if there are any such patterns?
If my impression is correct, what could be possible reasons for this tendency?
(Could it be that all his comments are what he received from his teachers and he only mentions them in the few cases where he disagrees?)
Do any Rabbinic sources discuss this?
A few examples:
אבל רבותי פירשו
כך נראית שיטה זו בעיני ולא פירשו רבותי כן
כך לשון רבותי ולבי מגמגם
כך פירשו רבותי וכן מצאתי בתשובת הגאונים ואיני יודע מהו
כך פירשו רבותי ולבי נוקפי
שמעתי כל רבותי מפרשים דקדיש בכספא דקידושי דרבנן נינהו ואי אפשר לומר כן