Can you show the whole plant and tell us where you are located?

I'll try to get a picture today. (it's in my community garden, not backyard) I haven't watered at all because it's been rainy. It's in a raised bed with soil that drains moderately well....but it has been rainy a lot. It's young. I just got it from a garden center last month. Pretty much all the leaves look like this.

Cleveland, Ohio suburb

One of the biggest problems and causes of lavender dying out is excessive soil moisture for those plants grown in the ground.
Lavender grows in loose, slightly sandy or gritty alkaline soil that is
fast draining. Over-wet soil conditions leads to fungus and root rot problems.
This can cause wilted black leaves where the plant is dying back.
Treatment involves cutting back of the diseased areas and allowing the
plant to dry out.
Fungus can live almost anywhere. The most common fungii are
Botrytis (gray mold) and Pytophthora (root rot.) They occur principally
because of excess moisture either in the air or soil.

What can you do? Clear out around the plant as much as possible
such as removing dead leaves, stems or debris. Use a heat reflecting
mulch of coarse builders sand, pea gravel or washed shells. Use proper
spacing when planting to allow good air circulation.

Frequently, once started it is too late to save a plant suffering from this condition. High humidity in the air can promote this type of problem as well.
Lavender prefers loose soil that will not compact around its roots
preventing the excess moisture from draining away. Plant in raised
mounds to allow for proper water runoff.

If the top i.e. the new growth is fine, I wouldn't worry too much about lower leaves looking a bit scruffy. Newly planted plants undergo some stress but I'm sure your lavender will recover. And all plants shed older leaves eventually.