Mine was around eight months when she decided to start being disobedient about getting back on the lead.
That was the biggest problem we had I think, can't remember anything else, but it went on for some time and she was on a trailing lead for months until her recall became totally reliable, and that happened when I discovered dried chicken liver treats and we never looked back.
I think, like human teenagers, a lot of dog just get a bit cheeky and start pushing their luck a bit. Definitely, keep an eye out for your dog trying to run off and not coming when called. Having talk to other people about it, I get the impression that's about the most worrying behaviour as the puppy tries to assert their independence.
Pushing their luck is a pretty good description - they suddenly go, hmm, these things you're telling me to do, are they optional?
A bit like actual teenagers.
Recall's quite a common one, they either try ignoring you to go do what they want, or play that nice - I'm going to come close enough to taunt you but not close enough for you to catch me and jump about game.
10mos Labrador has been very naughty over the last weekend. Raiding bedrooms and chewing belongings. Books, glasses case, Lego, tissues, loo roll, toys.... Honestly he's always been lovely, but this last weekend he's snuck upstairs and been destructive. I think that it's more likely to do with routine change due to dc at home for Easter.