Does trans fluid wear out

Correction I believe the trans is a 45rfe . I,m leaning toward an electrical glitch. Today it seemed to slip but felt like it was in second taking off twice and when I pulled over and shut the truck off and restarted it the problem disappeared a while.Twice today it downshifted hard as i was slowing down around 5 mph. It felt like someone bumped me from behind. Talked to a local small shop trans tech and he said hehad a truck that started doing this and he sold it.lol