The standardized probability of a normally distributed data is given by
P(X < x) = P(z < (x - mean) / standard deviation)
P(X > x) = 1 - P(X < x)
P(X > 125) = 1 - P(X < 125) = 1 - P(z < (125 - 100) / 15) = 1 - P(z < 25/15) = 1 - P(z < 1.667) = 1 - 0.95221 = 0.04779 = 4.8%
Though it cannot be said to be usual, at the same time it is not unusual because 125 is above the first standard deviation of the mean but below the second standard deviation of the mean.
