Toyota has faced a production bottleneck

If the number of sales continue to increase for the Toyota Camry the way they have in the past few months, 48,000 a year won't be enough. But, giving the Prius production the freedom to go its own way will certainly free up Toyota from the limitations it has faced in the past. Prius sales have only been limited by production numbers, not demand, this year according to Toyota.
Source: Camry Craze - AutoWeek

Some inventory relief will come this fall when the Georgetown plant begins building 48,000 Camry Hybrid models, about one-eighth of Camry production at the plant. That will free up Toyota's Japanese export allocation for more standard Camrys, while the Japanese hybrid plant can concentrate on Prius production.