Ok, the world of dog-to-dog interactions is all still a bit new to me. I need some help here.
As many of you know, Jack is our two-year-old male Corgi, who we have had since he was a puppy. He is a happy-go-lucky guy. In playing with other dogs, he is very confident in showing dominance (always wins wrestling matches, pins other dogs or has them willingly roll over and show belly) but he is never aggressive. I've not seen him growl at another dog, and on the rare occasion when someone would try to start a fight, he'll run. So he's normally fairly dominant with happy well-adjusted dogs, but not wiling to force the issue with those who are aggressive.
Madison is our new addition. She's a nearly-five-year-old female who we just brought home three weeks ago. She is fairly submissive. Jack has not bullied her, but he will do some dominant things like hook his paw on her shoulder or put his chin over her shoulder and gently nip at it, or jump right over her if she's lying in his way and he's running.
Jack is very intense when he plays. When he is chasing a ball, there is much play-growling and sliding and a mad gleam in his eyes. Madison has seemed a bit intimidated to play with him. They have gotten along just fine; they'll touch noses and greet each other. No mutual grooming or cuddling, but they are still getting used to each other and it's been warm enough that they don't want to lie down by us, let alone each other. Maddie has made a few half-hearted efforts to play with Jack, but nothing much. Jack will ask her to play but she's not been too sure.
Well, yesterday she started chasing him if he was chasing a ball, and I thought she was moving towards playing with him. Now today, whenever he tries to run, she starts to hump him. I have gone online and while some behaviorists say humping is generally a sign of dominance, others say that is not always the case; lower-ranking members will hump higher-ranking ones to gain status within a pack; dogs will hump if they are over-excited in play as well. And while some sources say a dog allowing itself to be humped is a sign of submission, others say that a confident dog will often simply tolerate it and act as if it's not happening.
If she is just over-excited, I would like to redirect the behavior as it's a bit obnoxious. If in fact they are sorting out their own "rank" between each other, I don't want to get involved unless there is a show of aggression, which there has not yet been.
Jack's reaction seems to be bemusement. He walks out from under her. He tries to wait her out. If all else fails, he'll turn and mouth at her (it's not even air-snapping; there are no curled lips or anything. I've seen dogs air-snap in warning and his snapping is not like that at all, more like the mouthing dogs do when they play). His mouthing at her will get her off, but then as soon as he runs she's at it again. He is not doing anything in any way, shape, or form that looks like submission to me. Toleration, perhaps.
Any insights? I don't want it to start a fight, and I don't want her to get obsessed with it, but I don't want to interfere with them sorting out their relationship either.
Edit: I wanted to add that if he does not have a toy in his mouth, he is immediately turning around and mouthing at her. However, if he's got a tennis ball, he is intent on keeping that in his mouth and that's when he acts like he's thinking "What the heck is this chick doing? Can't she see I'm playing here?" When he's chasing a ball, he's very focused on that.