Sounds normal to me..... A couple of Pixie's little front teeth fell out before the adults came in. I think it was about another two weeks before they started poking through. I've also noticed a bit of blood when I brush her teeth, which wasn't happening before. I'm assuming it's because she has a couple loose/missing teeth.
If you notice he's having a hard time crunching his kibble I'd probably soften it up a bit, but otherwise IMO, I wouldn't worry about it.
I'd keep checking his teeth whether he likes it or not. That way you can find anything that may be an issue in the future...
Although my pup has lost a few, she's retained her canines (she now has 4 of 'em on the bottom!!) along with a couple of her back molars. I'm going to have to get the vet to pull 'em or they'll end up causing problems.
