I have used neither Safale-04 nor done an AG stout before. I boiled yesterday and pitched some re-hydrated yeast last night at about 2000hrs. Little was happening this morning at 0730hrs except for about 8mm foam head visible through the sides of the FV.
Got home and imagine my surprise when I found....

It was half-way across the floor and making its way to the door. The picture shows after emergency mopping up.
Needless to say I wasn't very impressed...
...that I have wasted nearly a litre of beer. I only left three or four inches in the top of the FV, but this has been fine for all my beers for years. I have only ever skimmed to remove a small amount of junk from the top of two inches of foam.
And yes, that was a white towel on the floor.