These are the factors that would play into my decision: How long would it take? Do they offer free loan cars? Is there a 100% guarantee that this will stop the leak in one shot? Do I want someone taking apart any part of my factory built engine?
There isn't any way I would take this in if it were mine. There probably aren't even too many dealerships that would fix this unless they routinely push the limits of warranty. If you're going to take it in to get it documented, you might as well just have them fix it if you want to be with your vehicle for a few days. If it gets to a point and youre slightly out of warranty, and it gets WAY worse, their toyota warranty rep would have to decide if theyre going to pay for part or all of the repair. This decision will be based on your service history; the fact that this was documented a few years prior would be a mute point. I have seen it many times, as I have worked for a dealer (not Toyota) for nearly 5 years in service... If the minor seeps develop into puddles on the ground outside of your warranty your saving grace would be consistent service records with ONLY Toyota dealerships.