Is it incumbent upon me to repeat the fasting of the sixty consecutive days of atonement due to my misunderstanding of a sheikh's statement that the Quran is as ancient as Allah, and is ignorance excusable in this case, knowing that I am aware that the Quran is uncreated and is the word of Allah?

The Holy Quran is the uncreated Word of Allah. The assertion that it is eternal and of the same essence as Allah is an innovation (bid'ah). Imam Ahmad used to forbid delving into such matters, stating that the Quran is the revealed, uncreated Word of Allah. What is preserved from the majority of the Salaf is to refrain from delving into this and to suffice with saying that the Quran is the Word of Allah and that it is uncreated. The assertion that this talk is an innovation, not disbelief, and that the fast is valid, and that the whispers (waswasah) have no basis.