You know there have been some conflicts with Jetpack over the past two months. I don't use it, so I'm not sure if they've released any updates lately. Have they?
We are really not getting other complaints such as this, which isn't to diminish your topic but only to say it may just be a set of circumstances unique to your site, combination of plugins or server configuration. It's very hard to tell.
Meanwhile, some of the tools are coming from Twitter Bootstrap, so it's possible even Twitter pushed a change. Unfortunately they don't tell us what they're doing. You may not like hearing this, any more than i like saying it, but try deactivating some plugins to see if the problem is related to any third-party plugins.
I'll ask our developers as soon as I see them, if they know of anything.