Sounds like the noise my cat makes when he sees a bird out the window.
I completely agree with this. I think if I were you, from now on, I wouldn't greet Atticus right when you come in the house until he settles and then greet him with a pet and pat and go on about your business. If you make entering a huge deal he's going to freak out because he thinks that's what he's supposed to do.can be a few things (I have a dog who does this nd i looked into it)
1- mle dogs cn do it in rection to smelling hormones
2- dogs can do it in time of stress or over stimulation.
If it was me- i'd just try ot make the coming home less stimulating. It's not a big thing but being WHEN it happens- i'd be worried that allowing him to continue with this behavoir could be things that lead to seperation anxiety etc