Does she usually reply with the same reassurance? Maybe she is trying to help you grow by not giving you that reassurance? When i was in residential, one of the biggest things most people were guilty of was reassurance seeking... and the therapists were very aware of that and therefore did not give reassurance, as a way for the patient to learn self coping and self soothing techniques. just a thought...

if it really is bothering you, i would bring it up to her. i don't think she will think of it as intrusion on her personal life. she probably has a good explanation for why she isn't replying: maybe a personal issue, busy schedule, etc. i think you should talk to her about it before you assume things and get angry and hurt.