I agree management appear honest, hard working and competent....

I agree management appear honest, hard working and competent. However, I think they could do a better job setting expectations regarding their project plan. They've communicated P50 dates (50% chance under, 50% chance over) rather than explaining that their estimates for a range of possible dates and certain risks would push out those dates.
By sharing the whole, probabilistic project plan, risks and reserves the market would be fully informed and it would be clear that this was well within the plan (if in fact it was).

Hopefully they had identified this as a risk ahead of time but assigned it a relatively low probability. Hopefully they evaluated boring but the cost benefit wasn't there. Just because you hit on 16, doesn't guarantee you'll get A-5, it's still the right thing to do.

Lots of hopefully's there but no reason to believe that a rigorous project management system isn't in place. Anyway a < 1M slip isn't so bad.