I've had this happen at least three times that I've noticed...I'll be reading a thread and then scroll around, wonder why someone was given a 'thumbs down' for a perfectly good post so I give them a thumbs up to balance, then the thumbs down disappears and I know that I must have done it in the first place...whoops.
Other times if it seems like a mistake by someone else I've reported it.....
Mine happens on a tablet, I imagine it's even easier to hit the wrong button on a phone?
No ideas for a solution...just hope I haven't left a trail of mistaken ones...although I do use the button deliberately sometimes
"We're all just walking each other home." -Ram Dass
"Be a lamp, or a lifeboat, or a ladder."-Rumi
"It's all one song!" -Neil Young