Let`s hope that Mods join in to comment.
I have stated on this Forum probably 3 times that no problems have been reported on Gearbox/Transmissions with Toyota/Lexus Hybrids and I`ve not been corrected. However, yours is on 220k plus, so I suppose that there always has to be a first time.
As some consolation however Adam, my Merc is on 247,000 miles on its 5 speed auto transmission without problems, so you should not worry too much.
Ask your dealer to tell you how many defective Hybrid Transmission THEY have they fixed.