Ask your powder coater for some powder when you get your frame back, sometimes the powder can be dissolved (melted) in thinner and used for touch up. Sometimes the color matches good, sometimes not.

A friend of mine owned a powder coating shop and I worked with him sometimes when he'd need help. Powder coating is a skill, just like painting and a lot of the durability/quality is in the prep. We had different tanks of solutions to dunk the parts into before coating, depending on their material. All parts were bead blasted prior to chemical cleaning and then coating. There is also different kinds of powder and it does have a shelf life. Old powder does not apply as good as new powder.

I view powder as a utility finish and wouldn't powder coat a frame that was considered collectable.