VN5E016AH has unexpected voltage drop at zero load current

[scott239955_stm1_stmicro_com]

With zero load current, I'd expect the voltage drop between VCC and OUT to be essentially zero, since the on resistance is supposed to be 0.016 ohms (T = 25 C). Instead, there is a drop of 33 mV. VCC is 5 V. The datasheet lists a parameter of Von, called "output voltage drop limitation", with a typical value of 25 mV. No other information is given about this parameter. Could this be related to what I'm seeing?

Thanks,

Scott