Depends what sat on it. Put the right acid on it and it is reasonable for it to fail in seconds. As a result, you will have a hard time arguing with Subaru that it should not have failed so quickly. Under the right conditions, it can fail very quickly.
I will reiterate, the photos do not look like it is down to bare metal. Photos look like a clear coat that was unevenly eaten through (common with surface contamination). You can see it in person, so I will defer to your judgement on the extent of the damage. You can certainly ask your dealer about it and see if they will fix it. I doubt they will, but you are only out time and possibly some frustration for asking.
If it is down to bare metal, you will want to get it corrected. You do not want the aluminum hood to start corroding and the damage to expand.
