Question re: sodium content in hard cheese

My little guy (nearly 1 year), is not such a big milk drinker any more - he likes his food and water for the most part except for his wake-up milk and bedtime milk. The GP advised that so long as he is getting plenty of calcium from other sources and eats a wide variety of healthy foods, this isn't a problem. He likes cheese and I give him organic cheese almost every day to munch on while I prepare his meals. Only last night did it occur to me that cheese has a decent amount of sodium in it (339 per 100 grams of cheese or 85 per 25 grams of cheese & my guess is that he is eating about 25 grams/day) - is it too much for his little kidneys? I've been trying to google the answer and keep on getting results that just aren't that helpful.

PS - there is no other sodium in his diet...except for what is in the wheatbix he has in the morning.

I think that different cheeses have quite different amounts of sodium - swiss cheese and mozzarella are lower than other ones.

85 mg is still less than 10% of the adult "dose" - unless he's really tiny that would seem reasonable to me.