any pics etc of what you did to be proactive against this leak?
No pics, its pretty easy. Same thing this guy did in post # 1 here:

3rd brake light gasket replacement
I decided to change my 3rd brake light gasket before it started leaking. Is this the gasket everyone is using? Also, it feels like my 4 mounting screws bottom out when I tighten them. Anyone else experience this?

There are multiple other threads about this as well, but this one came up the fastest when I did a search. Unscrew the CHMSL (Center High Mount Stop Light), also known as the 3rd brake light. Take it off. Scrape/clean off the old gasket as best as possible, then peel off the backing from the new seal, and put it on in the same place as the old. Put back into place, reinstall screws. Do not overtighten too much, it is just plastic.
Some instead do a sealant or caulk of some sort around the existing seal, which is one of the TSB solutions for the 4th gens brake lights leaking. I wanted a solution that I could take the light off and put it back on later without creating a mess or extra clean-up work.