Yellow spots or streaks that do not turn brown quickly usually indicate an iron deficiency. In the warm months bahiagrass grows so rapidly that it often cannot pick up iron from the soil as rapidly as new growth is produced, resulting in the iron deficiency symptoms you have seen. Iron deficiency is likely to be a recurring problem in alkaline (high pH) soils. Iron deficiency can be corrected with applications of iron supplements such as iron sulfate or chelated iron. More information on iron deficiency and other aspects of maintaining a bahiagrass lawn can be found here: http://edis.ifas.ufl.edu/lh006