Yes, there is a weblog, as the body of the question shows. It's bigger than the data returned as described there. Let's move on to how you access it. On the "how you found out" front, here's how I figured it out:
I just found out about PaperTrail by selecting the "elements" item in the menu that opens if you click the little grid of squares in the upper right hand corner of Heroku. It looks like it might be useful, but it looks like it works on an existing weblog, and if my weblog only goes back for something less than 28 hours, it won't be very useful.
That same little grid of squares also had a "Documentation" item, so I clicked it and searched for "weblog." It turned up ONE hit, and it was an article about "Heroku for java developers." From that article, I found that "weblog" is mentioned because the article talks about something from Weblogic. On the main documentation page, there is a section on logging which explains that Heroku uses Logplex, which "is designed for collating and routing log messages, not for storage. It retains the most recent 1,500 lines of your consolidated logs, which expire after 1 week." And the error email came yesterday, so it would not have expired yet.
How to access
The page on logging refers to the heroku logs
command, which I tried. It returned the last 100 lines of the log (more than I got through the "View Logs" command). Further reading shows that I could get a list of the log entries from the time of the error email using heroku logs -n1500
and piping it to grep:
heroku logs -a secret-castle-56545 -n1500 | grep "10T22"
I was not able to use the filter string "-01-10T22" even with the quotes because it complained about the dash. If you have a comment on how to get around that, I'd appreciate it.