It isn't anything to worry about. They might, or might not correct themselves. But in the end it doesn't really matter at all.

A percentage of the populations (from memory something like 7 in 1000) have inverted nipples for life.

It is a congenital thing that is usually passed down in families so you will probably find that there is a history of it in either your family or your DH's - but short of asking everyone to whip their shirts off it would be hard to tell