I would argue that most parents feel this way, if they're honest with themselves.
When your 3-year-old climbs onto your lap and asks, "Do you love me the best, Mama?" ... what do you say? "Well, yes, but not as much as I love your Daddy?"
I don't think so.
And yet, when I got pregnant, I received some not-so-gentle advice from the older women in my life: "You're going to love this baby more than life itself. Just don't tell your husband," said one. "You don't want to neglect your husband, dear. Let him know he's still the most important person in your world," said another.