Hackers are using emails registered from databases they've collected to try and brute force passwords to guild wars accounts. Many people have been receiving password reset request spams to their emails. This doesn't guarantee they've been hacked but obviously it means you aren't safe if you're getting these. There are major security loopholes and flaws in arena net's password recovery system and it's flimsy at best. For now you can use the information provided in the link below for the best chance at staying safe until Authenticators and enhanced account reset options are added.
Also, if you have a gmail account, I HIGHLY recommend enabling google two step authentication.