About 15 minutes ago. It was aggravating because I couldn't use the back button, but I discovered I could hold it down and go back in history prior to the resource limit interruption. I think it's a random glitch and doesn't actually mean anything.
I haven't gotten it, but someone was kind enough to report it using the feedback, so I passed the note onto the devs. I'm not sure if it's browser-specific or what, so if anyone else wants to help us track it, please use the feedback and describe what you were doing, what page you were on, and what browser/ device you have, it may speed up correcting it.