I think your question is more of a "bucketing" question rather than any specific determination of whether an account is "new."
An account is an account, from the day it is opened, in your CR. Its raw effect on such calculations as AAoA dont magically change at any time, such as 12 months, 18 months, 24 months, or 100 months.
What may change is the impact of the account on how you are "bucketed" by FICO. This means how FICO will determiine which one of about a dozen scoring decisions they use to place you under a specific scoring algorithm. Addition of the account itself my have moved you from a "thin" to a "thck" credit file
Know one knows the criteria used by FICO to determine your acoring "bucket." Its passage from one year to more than one year may have moved your credit file from "thin" to "less thin," when considering all accounts in your file, but there is no public information released by FICO that would lead anyone to predict the impact of the monthly aging of one account on your score bracketing.
Most everything I have read on credit scoring summizes an AAoA of around 7 years to result in significant FICO bucketing. But just my experience.
I certainly would not expect the turning of one account to over one year would have any significant effect.
