If you are referring to the different color and fine felt-like residue, this is normal for Rhododendrons of this type. The brown-tinged fuzz is called indumentum will wear off in time as the leaf matures. Here's a brief blog post by the American Rhododendron Society on this phenomenon: http://www.rhododendron.org/blog/?view=plink&id=181

If you are referring to the dried brown leaf tips, then the plant may just need water. Check the soil about a finger's depth down (past any mulch) and see if it feels moist or dry. If fairly dry, a good soaking will help rehydrate the plant; rhododendron roots are fairly shallow and they have limited tolerance for drought. While the brown leaf tips won't heal, regular monitoring for water during hot, dry spells should prevent further desiccation from occurring. https://extension.umd.edu/resource/watering-trees-and-shrubs

Aside from this, the plant looks to be in great condition.

Miri