I think it's probably from the abundance of water they've received. We've been watering regularly this spring and summer due to new sod in the backyard that was put down after the addition was completed. We have three Crepe Myrtles and they're all performing the same way. It's amazing to see how flexible the clusters are and when it rains they bow their head even more.
Soon this amazing show of color will be over and all that remains will be the Lantanas which are performing in a similar manner.