A couple of points. One is that the transmission fluid should be changed every 30k miles just in case this was not done and the first fluid change was at 89k miles.
Two is just how was this fluid change done? The proper way is to change the filter, clean the pan, and then flush it. Some (maybe many is a better word) flush only and do not do the pan drop and filter change. This means you could be driving around with a partially clogged filter (which does affect shifting) and/or possible a low fluid level. The latter can also cause a transmission to go stupid.
With tongue firmly implanted in cheek, I would think from the reputation that a Toyota transmission would easily go half a million miles with no fluid in it at all. 