Hi
Since I live in Australia, I am not 100% sure what your routine retina screening involves. However from my experience and I do have retinopathy. there are a number of tests they can do to investigate properly, these include photographs of the eyes, they can also inject contrast dye and take images of the blood vessels in your retinas. I imagine you have already had your pupils dilated to give them a good view of your retinas?
I know it is easier said than done to not worry, but try and feel a bit reassured they are on top of things asking you back for further testing or discussion. Many people with initial background changes (and you have no reason to suspect this yet) go on to tighten their control, have constant review by the specialists, and progress no further. Hope you come back to tell us that