So, something that isn't really clearly explained in the literature or training, the XREAS system doesn't always have to be replaced wholesale.

Basically over the years we've found that if the leak isn't very serious (just seepage, not like a drip or a run of oil) then you can get away with a one time replacement of the shock.

The factory recommendation is to replace the entire pair including the center dampener, that's still the preferred way to do it; but warranty doesn't usually go along with that unless you have a lot of documentation (then again, don't get me started on warranty and their annoying crap.)

All that being said, XREAS is broken into three main components, the front shock, the center dampener, and the rear shock. There are disconnect points with check valves, so at most you'll lose a couple drops of fluid and no pressure loss in the system (this is why if the leak is minor you can get away with just a shock replacement, because the pressure in the system hasn't bled off through the leak completely.) So what happened is probably that your conversation with Toyota Financial got them to issue a one-time goodwill of all 4 shocks, but since that side of things probably doesn't realize or care that there is also center dampeners they only authorized replacement of the shocks.

At the end of the day, you're probably perfectly fine and your system should be as functional as it was when you bought the vehicle (I have only seen 1 XREAS shock fail drastically requiring the replacement of the center dampener and companion shock, and that was at 55K; the rest have been relatively minor seepage.)

I apologize for the information dump, but hopefully that helps put your mind at ease.