How many standard deviations is Sensor / Component Uncertainty (+/- X) given in?
The tolerance of 1% tells you nothing about the statistics of the actual values. The mean of the actual values might not be the nominal value. The distribution of actual values might not be gaussian and might not be uniform, either.
The tolerance of 1% is telling you that the manufacturer guarantees that all actual values are within 1% of the nominal value, nothing more.