Our app has a cyclic usage pattern and all is quiet right now. So rather than freaking out about it, I'll just let someone at Heroku figure it all out.
It would suck if it happened during our busy period, but then again I could say "We're working on it." and just assume the Heroku team will fix things faster than I ever could have with my limited *nix admin skills.
I get that you're saying your users don't care/didn't notice, but I'm clearly missing something because if I had an app on Heroku, I'd be a little nervous. When the cyclic nature of your app swings back around and it's in regular use again, this kind of outage might not be so magical.
Users surely noticed, but Heroku definitely noticed before my users did. They're quietly working on a solution and I can quietly go about my day. If my users start complaining, I'll have time to talk to them; time I wouldn't have if I was neck deep in log spew.
Having run apps on my own servers before, I know what a pain in the ass it is to deal with downtime yourself. I'm not particularly good at it, so I appreciate having experts take care of it for me.
This is downtime coming from their infrastructure, not your app.