I believe that the meters in DSLRs that I have (D50, D200) are calibrated to underexpose slightly in an attempt to stop highlights burning out.
That may not be totally correct but I do believe that they behave differently to meters for film cameras because of the sensor.
I'm sure I read something along those lines in AP a few months back but, not thinking about getting back in to film at the time, I sort of ignored it .