Yes they look fed, they are 3 days old now and look well like she takes care of them so you don't need to worry anymore and don't even have to take them out of nest every day, it was necessary to check if they fed first couple days just to be sure she has milk and taking care of them, now they should be fine. You can just check every couple days without taking them out, maybe you will want to change soiled hay in their nestbox on day 7-10, since they are only 4 it shouldn't be too bad if you prepared it as suggested. Then you can prepare some box with a napkin or paper towel to put them in while you are cleaning their nest quickly, then put them back. You can take more photo then, they will have some little fur but still with eyes closed.
Now just make sure their mother has everything she needs to produce milk, unlimited hay, unlimited high protein pellets (junior pellets usually have 16% protein and higher calcium) and plenty of fresh water, also her usual greens and treats.
Make sure she is not stressed, has shelter protected from sun and make sure your male and she are very separated, even if you already neutered him he still can get her pregnant up to 6-8 weeks after neutering, it would be very difficult for her produce milk for her babies and build bones for the next babies in her belly so she will be very exhausted and her next babies can have some birth defects, please take every precaution they have no contact until babies are 8 week old at least. If you are thinking to breed her again please let her recover at least a couple months after she stopped nursing, even commercial breeders give one month to recover. We had some threads even here when people let them breed with very short recovery period and babies were born weak or deformed and mother was sick, it is very unhealthy to let them have more than 3 litters per year.
I say that just in case I don't remember now you probably said that you are going to neuter them.
