^^about a month ago i got around to repairing some rust around the mount you're talking about...i'd suggest not putting it off, as it'll eventually eat away at the actual shock tower if gone unchecked...
the front wheel wells consist of very thick sheet metal peices shaped to form the tower, and seam welded at the top...the forward peice then runs forward to that mount...and just in front of the mounting bracket, it stops (at about the 1 oclock position if looking at the wheel)...to finish the well, a super thing piece of sheet metal is layered over the thicker flange, and goes to around the 3 oclock position before staying flat and goes up to the head light area...In the well, there is a seam weld exposed to everything...that is what happened with mine, that weld rusted out in a few small spots, allowing water to wick up inbetween the thin and thick metal layering...
its very hard to explain what i mean...but was pretty simple to fix...i just filled the holes, used por-15-like rusted metal treatment, and 3m rubberized spray to undercoat the entire forward section of that wheel well...hoping i stopped it...I can see why that seam weld would fail, though...the factory does not spray that section with ANY undercoating...it was just bare galvanized steel in there, which has held up surprisingly well...but a thick coat of undercoating would've prevented it completely...
i'll be dealing with the passenger rear fender as early as this weekend, hopefully...we'll see if that one is any harder to slow down...