The earliest source I can think of is Rav Hai Gaon.
I apologize that I can't give better a citation, but a Rosh Yeshiva once told me he saw a responsa from Rav Hai Gaon, with the following question:
There is a Christian Priest in my town, who is very knowlegable regarding Tanach and has good approaches to the text, am I permitted to ask and learn from him?
Rav Hai Gaon's response is: Mekabel Emes MeMi SheAmro, take truth where it is found.
Also, the Abarbanel in his peirush on Tanach will quote Christian sources' interpretation of pesukim. Most often he rejects their claim, but sometimes does accept it as an approach (especially interesting, since he was chased out of Spain by the Christians during inquisition). That being said, the Abarbanel may not be mainstream in this regard, and I know of at least one right-wing Yeshiva that purges its shelves of his contributions.
Short answer is: yes, that's fine. But you'd better have enough background information to know if it's really "Torah".
Update: A friend of mine just found a promising source for the Rav Hai Gaon story, not sure if it is the same one I heard since it is a bit different but certainly close enough to suspect this is the case:
אגרת שהכילה את פרשת חייו של רבינו האי גאון ז"ל ודרכיו המשובחים ובה מסופר שיום אחד נזדמן בישיבה הפסוק שמן ראש אל יני ראשי ונחלקו המסובים בביאורו וצוה רבינו האי ז"ל את ר' מצליח שילך אל הקתוליק של הנוצרים וישאלהו מה הוא יודע בבאור הפסוק הוה ורע בעיניו וכשראה ז"ל שקשה עליו הדבר על ר' מצליח הוכיח אותו לאמר הן האבות והקדמונים החסידים והם לנו למופת היו שואלים על הלשונות ועל הביאורים אצל בני דתות שונות אפילו רועי צאן ובקר כידוע
Also, while clearly not baring the same level of authority of precedent as the previous sources, here is an interesting story related to the subject.