Two rather obscure possibilities come to mind:
1) A week ago, the server was relocated from Lithuania to Chicago. If you're not in North America, it's possible that the network latency to reach the server may have increased by as much as a few hundred milliseconds. The difference wouldn't be 5 seconds, however.
2) Fan speed is not set based on the GPU load, it's based on the GPU temperature. Perhaps the ambient temperature is cooler in the room where your computer is located, either because the weather got cooler, or air conditioning was turned on. This could cause a delay in the fan speeding up, although not necessarily a delay in the crunching.
My lucky number is 75898524288+1