Yes mate quite likely. That said the metal underneath seemed pristine and I couldn't see any real problem from behind with the lamp cluster out. I think in my case some surface rust had developed on the seam in the light cluster cavity and had managed to gradually work it's way under the paint. Definitely doesnt seem to be the case the whole panel is being eaten....but that's only what I can see. Will keep an eye on it and look to get it addressed in future if it persists to be an issueYou probably need to get that cut out and new metal welded in. They rust from inside out. Surface repairs won't work and as you know end up being a waste of time and money.
A larger rust patch under my rear light turned out to be the result of surface fixing that never addressed the source of the rust. Became a much bigger job.