It's because with the move to the new lot it makes that area seem like a surge because that's when people are turning on their phones and opening the lyft app. The prime time algorithm is really based on # of ride request to # of drivers it's really bases on how many people have the app open to how many drivers are in the vicinity. So when people are opening their lyft app (the person is now a potential ride request in the apps algorithm) the app sees that there isn't an available driver in the vicinity it triggers a prime time.
The only benefit to this as a driver is the fact that the darker the pink the probability of the queue moving s little faster for a bit soon.