TMP05 offset

I'm using 96 TMP05 'B' grade temperature sensors in daisy-chain mode, powered by a low noise 3.3 linear regulator. They all seem to read high by about 3-5 deg C . I have checked this with a temperature probe. The sensors have good air flow around them and are not near any heat generating components.  Each sensor is closely bypassed by a 0.1 ceramic cap. I am reading the output with an FPGA, and I have verified the high and times with an oscilloscope. I have verified the packages are marked 'T8D' for B grade.This has been consistent over several rigs using many sensors and several FPGAs. The specs seem to indicate I should see a max of +/-1 deg C error. What could be wrong?