In the Data Collection guidelines that are agreed to at the time of upload it states that you should use at least 75/75 overlap for general purpose mapping.
With marginal overlap like that and terrain that is gently sloping it is really easy for it to fall apart quickly. Based on your previous overlap reports it looks like they were about to fall apart as well but you got lucky those times... It appears your luck ran out!
To take luck out of the equation and to prevent having to refly an area we highly recommend using 80/80 overlap and using Terrain Awareness if possible.
We will grant a one-time 50% refund for overlap related issues. Rerunning the same images will not yield different results.