show "age" of last update in modeline?

Sometimes my offlineimap process hangs or something, and I don't always notice since I have a hook to run it on entering gnus, and I might quickly check gnus if there's anything new, see nothing, and then think there's no new mail because I forgot to wait for the modeline to show a flag. So I put some advices in my init.el (https://gist.github.com/unhammer/b900b447292ea79b08d9) to give me a hint that I might have to prod offlineimap a bit. This just writes how many minutes have passed since the last time offlineimap ran (if >10min) in the modeline. Would something like this be interesting to have in offlineimap itself? (obviously not implemented with advices)