Below is most recent response from VA on this:

NOVs are valid for six months in the system. However, an NOV on a purchase is always valid as long as the contract is valid. If the contract is still valid, there would be no need to reorder the appraisal.

Original question:

Our VA appraisal (for a 2x loan) was reviewed and approved prior to construction closing. However, we are 30 days from permanent financing closing and I am showing that the appraisal is going to expire. Can you confirm how many days a VA appraisal is good for?

Our system is showing 120 days but for some reason I am thinking it should be 180 days. Thanks!