We had a space issue in one of the servers and had to flush the gradle caches. That probably meant a temporary slow down as gradle had to re-fetch some files.
Even after your dependencies were fetched this applied to other users which resulted in a queue. The other servers didn't have as much gradle caches so we're guessing that they were also slightly slower when they did pick builds.
Overall caches should be up to date today/tomorrow and builds should be at their usual speed. Let us know if they aren't.