Are they litter-mates?
The play thing is normal. If you don't feel comfortable you could try breaking them up when they get really excited, but they're dogs, so they have signals (IE pain yelp) and they'll stop if one screams uncle (or bloody murder).
As far as hacking ... was it during being really excited? Or maybe after chewing on something? Mouth full of hair from wrestling?
If it comes up and you can narrow down what elicits it, that's best, or you can tell your vet the concern and they'll check the throat a little more closely for anything ...
__________________  Stash, Poco & Wicket, Mogli,
Benny  |