Cross-pollination wouldn't cause a color change in the existing shrubs, but might in any "daughter" shrubs - cross pollination affects the children, but not the parents, per se.

Have you done some major pruning? Maybe you pruned off branches of one color that had been grafted onto a different color root stock, as is sometimes done, so the original stock is now flowering.

Have you done any major fertilizing or anything else to change your soil's chemistry?

Azaleas need more sun than we get in my yard, so I am not an azalea 'expert' just sharing what I do know.