I have seen something similar alright now and again but I didn't think that much about it - So in answer to your question yes I have but it is one of those things that I didn't notice that much, I am not as eagle eyed as you are.
For about two weeks now I have been getting notifications of up votes , yet when I click on it there is also a comment that I wasn't notified of. Crazy shit. The comment is more importiant to me than the up vote
Do you see this issue happening on your own questions? For opinions or for opinion comments, or both? Or do you see it also for new comments for your opinions on other users' questions? What device and browser are you using? Thanks for the feedback