DESeq2 Dispersion Estimates Curve Poor Fit?

PlotDispEsts returns this plot after running DESeq on my RNA Seq dataset. It looks somewhat different than example plots I see online - many of the points fall below the line of the expected dispersion for genes at a given expression level. I thought the line should be fitted to my data, but it doesn't look like a very good fit to me. Has anyone seen anything like this before? I'm new to RNA Seq analysis and am wondering if I should be concerned by this plot.

Thanks for your help!