Does a single, isolated error in prayer, such as saying "Subhan Allah wa bihamdih" during the bowing (ruku'), necessitate the prostration of forgetfulness (sujud as-sahw) after the prayer ends?

There is no disagreement among scholars that the Imam bears responsibility for the forgetfulness (sahw) of those praying behind him (the congregants), except for deficiencies in the obligatory acts. If a congregant makes a mistake without the Imam doing so, there is no prostration of forgetfulness (sujud al-sahw) required of him, according to the general consensus of scholars. The proof for this is the saying of the Prophet, peace and blessings be upon him: "There is no forgetfulness (sujud al-sahw) upon one who is behind the Imam. If his Imam makes a mistake, then it is upon him and upon those behind him." Therefore, your prayer is valid and nothing is required of you.