Vacation Days

Does anyone else ever feel guilty for asking to use their vacation days? I get two weeks off per year. I usually take one week long vacation and 5 individual days off. I always give plenty of notice and, unless it's something that just can't be changed (like my upcoming wedding/honeymoon), I usually try to be flexible with the dates because, if I can help it, I don't want to take off if it happens to be a really rough day schedule-wise for them. They don't really have reliable back up care, so the mom has to take time off work, which is difficult for her to do. They give me two weeks paid, but I just can't help but feel guilty when I use them. I think it's because it's not like an office job where things keep moving even if I'm out a day or two. It disrupts things for them and they are so good to me that I hate doing that to them (they have NEVER tried to make me feel bad for taking off. They have even given me non-vacation time off for appointments and things). Does anyone else ever feel this way?