Hi Leegelez, I have a 5 month old male and he started to lift his leg recently as well. I believe it's a monkey see monkey do situation as my Y.T. has a older sister who does the same thing (but only on walks.) My vet says its due to a few things. Some males will continue to squat female style if that is all they see. My girl Y.T. will lift her leg on walks and sometimes do a hand stand pose to make her pee marking high on the post/bush etc so that the next dog that comes along thinks she is bigger due to the fact her pee scent is high up. So maybe your Rigby is noticing the other males at the park, trying to appear bigger or he is just cleaver. I'd give him a gold star just for cuteness.
