Leaky stopper or did my stout ferment overnight?

On Sunday I brewed a sweet stout but had a bonehead moment (https://www.homebrewtalk.com/f14/had-bonehead-moment-while-brewing-today-305883/); I had to dig the stopper out of the neck of the carboy with a sanitized screwdriver and butter knife, so I'm worried that I damaged the seal on my stopper.

Yesterday morning, there was a 1" krausen and what looks to be remnants of a krausen that went all the way up to the neck of the carboy, but there is absolutely no airlock activity. I don't have access to another stopper at the moment, so do you think I'm in trouble/have a leak, or is it possible that my stout fermented so quickly that I "missed" the major activity (used Wyeast NeoBritanna yeast, no starter)?

There's a picture of the carboy.

The stopper might have a leak, but I wouldn't worry about it. The carbon dioxide will push out all the bad things trying to get in. Meanwhile, get a new one when you can. It is possible that fermentation happened fast and you missed it. It's also possible that it's happening without visible airlock activity. I had a batch that never made one single bubble in the airlock, and then the next batch I made in the very same bucket with the very same airlock was bubbling like a freight train..