I have a young Blue False Indigo which has been in the ground for a couple months. I just noticed this morning that the tips of some of the leaves are turning dark. I've heard that the leaves will darken as summer goes on--is that all this is? Or is it a disease, or something related to the incredible heatwave? Otherwise the plant looks great, very upright, very robust. It is in full sun and I've kept it well watered during the drought. Thanks for any info.