If the drive was sitting unused long enough for the water to start to come out of emulsion then it will form a cream like layer at the surface. Maybe something caused it to look a bit foamy (not sure what that would be).
Letting the water come out of emulsion and sit for an extended time is when damage gets done. I've seen boats in the charter
fleet with shaft seal leaks
which were in regular charter
use, so the water was mostly kept in emulsion, oil changed (pumped out so not 100%) in between charters, and sent back out on charter with no immediate ill effect (not ideal long term of course). Seals
changed when charter schedule permitted.