I've noticed a few other leaves nearby having the same issue, though not as prominent.
Does anyone know what this is? Should I be concerned?
This looks like Powdery Mildew, it's a very common fungal disease.
Try pruning the affected plant parts. Additionally, try to increase air circulation around your plants and avoid watering the plants from overhead - fungal diseases thrive in humid conditions, and decreasing dampness around your plants should help.
Naturally, applying fungicidal treatments is recommended, preferably one that is specific for treating Powdery Mildew, but a baking soda solution or neem oil should help too. Source