My 7 month old is grinding his teeth?

My son is 7 months. His 2 bottom teeth are fully out as he got them at 4 months and he has 4 on top that all broke through the gums within days of each other about a week ago. Since yesterday, every time we hold him upright we can hear grinding sounds (since he is so close to our ears).
Is this normal? My husband grinds his teeth in his sleep and did so as a child. Is this hereditary? Should I be concerned?
Emma’s Mumum,
Just curious, how do you find being pregnant with such a little one? Mine is 7 months and we’d like to ttc #2 very soon.