I have seen Cirque perform on off nights where lots of glitches occurred. They are still exceedingly great. Go again and see it with a different perspective. I still adore them all. If you perform in a large venue, you get "off" nights.
I have gone to the same show several times just for that. It's worth it and yes it humanizes it when mere mortals make mistakes.

"Do the mistakes bother you?"

Mixed bag.

What I enjoy most about cirque shows is the experience of awe.

Shows with flawless cold performances have no awe. They bore me. Older shows, and shows with many chorus acts sometimes have this element.

Shows with verve, beauty, and grace, can leave me in awe, even when the activities being performed aren't necessarily complex or difficult. Lighting, music, costumes, props, clever ideas, and grace in combination can all take my breath away, (literally).

Mistakes detract from beauty, from grace, and from verve. Yes, how they are handled does, in my mind, qualify as a mark of professionalism. And one mistake in a show, requiring a redo of the trick, doesn't bother me much. I actually enjoy studying some of the flaw shots on the dvd's. But we saw a lot of redo's the other night. To the point where I was tired of them.

While the show isn't 12 years old, we're also not talking about opening week here. They've been doing this show for months. I'm sure the performers are capable of the tricks they are attempting. I'm sure they have done them in other shows. And I'm sure each performer is sufficiently professional to manage numerous performances without a failure.

And I can understand when one person, on one trick, isn't quite as focused or in control as they thought. But when several seem to have this problem, all on the same night, I begin to wonder about the morale of the troop and to analyse and second guess what's going on off stage and that concern pretty much interrupts any opportunity I might have had to experience awe. Instead of experiencing the current act in it's current beauty, I begin to imagine all the ways it might fail instead and start looking for them.

So... mixed bag. In this case, yes, I found the sheer quantity of mistakes and redo to be intrusive.