My kids actually do the opposite. I SAH, so I am the primary caregiver, but DH is super involved when he is home. Because they miss him, when he is here they prefer daddy loads and unloads them from the car or put them to bed (oDS especially). And I usually go with it, because I know they just miss him. We don't do it any differently, they just want his attention.
If tables were turned though and they insisted on only mommy, I'd insist on hubby doing it anyway some of the time. I want the kids to feel close to both of us, and if they see him less and then also push him away when he is home, I would feel we need to work on it. They see me 24/7 and are comfortable and loving with me, so I'm not worried about it when they want daddy time. Once in a while it stings, but I think it is great that they are so attached to hubs. And I know I'll get snuggles later.
Now my youngest can be very rigid in how things are done, but it is more tied to the process/result than the person.
Wife to Joe. Proud, tired mommy to Captain Destructive (6/09), Sir Screams-a-lot (8/10), and another little miracle due 3/13.
Trusting God brings life. Believing brings rest.