Unfortunately it happens often.
Btw the sound alerting the player is very weak and the text on the screen may not be noticed too.
If the alert occurs during a zoning, it's a fail too.
I looked for an add-on but did not find one.

Yeah everyone knows how screwy dungeon finder can be, it seemed especially bad today though.

I was trying to run pledges on a tank earlier, I waited about 20 mins, which is highly unusual as a tank queuing for the day's pledges. So I figured something was borked and I tried to cancel queue and requeue, which usually works in that situation. Hit cancel queue, accept, timer is still running at the bottom of the screen. Ok, that's weird, but I've seen weirder. I exit menu, still says queued. Obviously I can't requeue until that goes away, so I went back to the menu tried to cancel a couple more times, and nothing.

So I log out and log back in. I queued again, same scenario played out. Whatever, I needed some skillpoints on that character, so I decided to collect skyshards for a lil while and try again later.

Like an hour or so later I'm thinking about my pledges again. I decide maybe I'll queue as healer this, idk why that would make a difference, but the tank I was on was a Templar who's capable of playing healer with just a gear swap, so why not. I go through the trouble of swapping out my gear, and adjusting my skill bars, which took a minute because it's not something I do regularly with her, and then I go into the menu to queue.

That's when I realize I'm still queued from before, timer is at like an hour forty-five mins, even though I had already "cancelled" it over an hour ago.

Frustrated, I logged out and started binge-watching a show on Netflix, and that's what I've been doing since.