Is it ok to email buyers of my Android app?

I'm a new Android developer and have released 2 different apps. RealMirror is free and I released it about 6 weeks ago. It has done, in my opinion, well with over 10,000 downloads.

Monday, I published my first paid app, mySoundboard. With no downloads at all for the first 48 hours, I was very disappointed.

Last night I had 2 downloads. I am very happy and more than just a little grateful. I don't have their real emails, but I do have a Google Checkout anonymous email address that I can use. Is it ok to email the buyers and say thank you or would that be too creepy?