Epiretinal Membrane?

Hi all.

I recently had an examination wherein the optometrist found what he called a "membrane" - from my googling later on it seems to be an epiretinal membrane although he never specifically used that term.

During the slit-lamp examination he didn't seem to notice it - it wasn't seen until he looked at the camera images (a whitish region was visible), at which point he gave me an OCT to confirm. It is outside the macula area, my (corrected) vision is fine with no noticeable distortion, and my prescription has been effectively stable for about 5 years.

I think he was a little surprised to find it given my age (30) but otherwise didn't seem to be too concerned beyond giving me an Amsler grid to periodically check and recommending more frequent follow-up exams with OCT scans. My suspicion is that it could have been there for a long time, since this was my first ever camera/OCT based exam (hooray for rural living).

I'm just generally curious about how commonly these are "incidental findings" and whether or not it's likely to change/progress?

Cheers