"My daughters have blue eyes, but their eggs can also carry the brown eyed gene because of their dad."
Nope. If they have truely blue eyes, they have two "blue" alles.
(Each sperm carries 1/2 of your husband's DNA. Just happens that the 1/2 they got was "blue")
The other possibility is that your daughters don't have "true" blue eyes, but rather hazel --- a mixture of blue/brown.
No speck of brown. Very bright blue eyes, just like mine.