And yes, those would cause weird shifts. Fixed that problem on my sister-in-laws trail blazer just by changing the filter.
Not o thread jack, but what problems was she having? My moms trailblazer seems to struggle to shift sometimes. I'll be getting on it when getting on the interstate, and sometimes it won't shift up when it should. Or I'll be driving through town and it'll sound like the engine rpms are high up, but under 2k rpms on dash. Seems like it just struggles sometimes. Wondering if this is the problem you experienced.
She was complaining of weird shift points and high revving and whatnot, but I took it for a test drive and got on it pretty hard trying to duplicate the problem, but didn't notice anything outta the ordinary. So all I did was change the fluid and filter, not a complete tranny flush... I advise against full flushes because some transmissions run worse afterwards. But she said that she hasn't noticed any problems since and it's been a year.