Interesting, on my alt account, I have the exclamation on the Quests button with no unfinished quests, but on my main account, there is no exclamation mark. The main difference I can see between the two is I have redeemed the Tuesday mission on my alt account, but have not yet done so on my main.

If the bug is still there are after tonight's update, I will run the Tuesday mission and see what happens.