From the USNTPS Flight Test Manual (publicly available
here):
Additionally, dihedral effect of the
airplane with swept wings is directly related to lift coefficient [i.e., AOA - my comment] (Figure 5.11) Airplanes with
sweepback will exhibit increasing positive dihedral effect with increasing lift coefficient;
these airplanes may tend to have excessive positive dihedral at low airspeeds.
and the figure:
(A note on collision of terms... the C sub L on the horizontal axis is Coefficient of Lift, as it says. On the vertical axis, the C sub L sub beta (also, graphically misaligned) is rolling moment due to sideslip - aka dihedral effect)