I had to google it because I thought I didn’t know this word and then I proceeded to facepalm myself. And it’s not like I didn’t see it in a long time, I saw it yesterday and quite possibly earlier today too.
Have you ever had a moment like this with any word? I hope I’m not the only one, cause making a mistake like this with one of the most common words hurt me deeply xd
Oh, absolutely. It never goes all the way away, in my experience. On the bright side, as long as you know one reading, it’s still much easier to look the word up! Just last night I was scratching my head over 初陣, which turned out to be ういじん! Rare/exceptional readings are annoying little suckers!
If you think about it, something similar happens even in alphabetic languages when you (I) glance over a word and misread it. Not exactly the same thing, but the point is it just happens.
Also, this is the first time I’m seeing 初 as うい.
Done the exact same thing many times. I quite often read 受付 as じゅふ as well 
. It really depends on the speed you’re reading and how much you’re concentrating. I also have a habit of looking at single kanji rather than whole compounds, but I’ve gotten a lot better over the last year or so at forcing myself to look at a whole word before I let my dumb brain shout out the reading.
Edit - Just remembered another word I tend to read wrong in haste. 出来事. Have read this many times as しゅったいじ. Usually as soon as I read the じ I also realize I am silly and that it’s できごと. 
I tend to do this with words I’ve never seen before lol. Recently put my phone in Japanese and saw “調べる” and despite not knowing the actual word/kanji, I’ve always read it as “とべる”. Upon looking it up, it’s actually apparently “しらべる” haha
Was reading some document that said 部室 literally over 10 times and then 部屋 comes up (which since it was one of the first words I learnt in Japanese is basically a core memory etched into my soul at this point) and somehow my brain stuttered like ぶぶぶぶや…ちゃう? ちゃう…へや…Shiii…まった。It made me realise I was tired that day lol
That’s what I thought too! It was late and I was reading Japanese for a long time that day. I decided to call it a day and wrote this post 
Sometimes kanji be making me feel like I’m going crazy hahaha
元気 isn’t one of the words I’ve ever misread (although I don’t put it past myself to do it sometime in the future) (at least, I don’t think I have), but there is one time where I saw it as a name and immediately read it as げんき, then immediately backtracked and went, “Oh, it’s a name here so it’s probably もとき.” It was げんき. Also I know his name.
I can’t think of any off the top of my head, but there are definitely other words I’ve misread despite technically knowing them. I comfort myself with the knowledge that it happens in English (my native language) sometimes too, and not even all the time when I’m tired.