I think you are right about drought stress.
You can signup here: http://www.turffiles.ncsu.edu/tims/default.aspx
for watering guidance. If you have irrigation it helps with adjusting your watering schedule based on microclimate data stations in your specific area (NC only).
As far as the rust spots, can't help you there. I know my Z had brown patch in the fall and it's back now, just had a fungicide app that seems to be helping and the NC Turf Files issued at Disease Alert for Brown Patch: http://www.turffiles.ncsu.edu/Alerts.aspx#005089
There is also a Disease Identification Aid here: http://www.turffiles.ncsu.edu/diseaseID/default.aspx
and don't forget Grub Treatment in June (also from NC TurfFiles)
May 24th, 2010. Japanese beetles are now beginning to emerge which means egg laying will start in ealry June. Effective applications of insecticides for white grubs will be mid June for much of th estate (a little later in the mountains). Despite the dry weather in April and early May, the beetles are right on schedule.