I do not think we can tag it "Rude" People do not answer for various reasons. I used to be very sensitive about it and but now have learnt to let it go. When we ask someone some info which is not "Critical" , we should not expect them to reply right away or answer. Its like "I" texted and you did not response. How dare you... I am still very quick in answering, but do not care if people do not bother to answer. As we all, she might have many diversions or might be compiling right answer along with other daily chores or tasks. I know it takes 10 seconds to answer. But she might be thinking let me find number first...oh, then she got busy with kids...or god knows, something happened. Your relationship with her also affects her response.