Part of me thinks it's unreasonable, but I'm going back to full time job and we're going to be apart for most part of the day. I think it would reassure her and also give me peace of mind if she had a very simple mobile phone with preconfigured numbers that she could use to call me in case of emergency or if she gets really upset.
Of course, I can also see this not working and I don't even know what the policy is in her school. 