eBay has begun sending such messages for each sign-in from an unrecognized browser. Unrecognized just means that the browser has no cookies from a previous sign-in to that account, or the IP address does not correspond to a previous sign-in. If you are erasing your eBay cookies or changing your IP address, that may increase the number of those messages you receive when you sign in again.
eBay is trying to provide an alert so that users notice when an unfamiliar sign-in occurs, to get an early warning that an account might have been compromised or hijacked.
For a list of all current eBay sessions, go to your Account, choose "sign in and security" and use the link to view sign-in activity.
Do the browser, location and time shown correspond to your own sign-in activity? If so, you can ignore the message.
Keep in mind that the location may not be precise; it may correspond to the location of the network rather than your actual location. In some cases, the location information may just be your country. Browser information may not always be available.
If you do not recognize the location, time or browser, and you actually suspect that someone else may have gained access to your account, you may want to change your eBay password.
