All depends on the style of the queue. Highly interactive, like the earlier parts of the Winnie the Pooh queue, where the kids have room to run around, I'd probably just go around without even saying anything. I consider those types of areas as 'sidetracks'. In those areas, it's not really going around, it's more like the other people stepped out of line. Partially interactive, like the later parts of the Winnie the Pooh queue, with the honey walls, I'd wait it out a bit, and then ask if they're moving up, if they mind if we go around if the kids want to play, or a gentle reminder that the line has moved on. Something like that.
Basically, it comes down to whether or not you're obviously going around. If you have to squeeze, then no. If it's like they've stepped out of line, then yes. And if it's questionable, like the barrels in 7DMT, then maybe, depending on the exact feel of the situation.