AIBU to feel the interview did not reflect the role?

[Corneliafunk]

Interested in opinions- I was interviewed yesterday for a project mgr role. I had done similar work before in the same industry. The JD was vague about what the actual project was- I thought it was a new IT system.
At the start of the interview more detail was provided but was still relatively vague (due to commercial sensitivity I assume).
The 3 person panel then fired v specific questions at me for an hour. Half way thru one did finally make it v clear what the focus of the role would actually be.
It is a v large non IT project that would have lots of HR, contractural and union negotiation.
By the time this was made v clear the interview was half way through.
I had prepared for what I thought the interview was about.
Has this happened to you before? I have been thinking about what the panel might have thought of my responses - some were ok, but I know others missed the mark as by the time I could have come up with better examples the moment had gone. I was completely exhausted by the end of the session!

Why did you think it was a new IT system?

The project was described in the JD as ‘operational model change’. Think of the industry as a large hospital’s busy inwoods goods and consumables mgmt area - and it had previously already changed from being an internal hospital dept to being outsourced.
Now it turns out they are going back to the original set up - I didn’t think they would make this type of change again knowing the turmoil caused last time.
And I was also working separately but in the next door office to the person who was updating and renewing the existing contract just before I was made redundant 6 months ago.
So i incorrectly surmised that the project might be something like a major IT upgrade