I think sometimes girls read between the lines of your email and get a feel whether they want to respond or not.
I quite often get ignored as I can be quite forward with what I like and given that I am a pervert sometimes they just don't reply.
I am always polite though.
Maybe this could form a discussion point ( I will bring it up as one shortly - How do you word your first AW email to a WG?), but it all depends on what a girl wants or likes on the first impression, which is obviously via an AW email. I'm sure you don't just say "Fancy a fuck on Tuesday?" or "Do you reckon you could handle my big cock?" etc. but I think a good intro may help. These girls do get a lot of time wasters.
I was talking this over with a wg recently. She said she reads a lot of BS in her email. I asked then why she replied to mine so quickly, and she said 'You got to the point, were polite, knew what you wanted and therefore were clearly not a time waster'
However, it doesn't work with all. There is one who has ignored some of my emails for a while (since having to cancel because i was out of the area for the day). She eventually told me in a very kurt way (actually quite rude) to make a booking. I'm now not sure if I want to see her now.
In short, I am sure you're ok. But I do think some consideration needs to go into what and how you phrase an initial email to a WG.