You've probably heard all about Heartbleed, a vulnerability in online security that was recently widely publicized. If not, take a look at our Proquest Newspaper Database and do a search for Heartbleed for the latest news.
Most people who took a poll conducted by Huffington Post/YouGov about Heartbleed did not check to see if the accounts they used online were affected.
Read this article from the Department of Defense to find out what you should do about Heartbleed.
You should always be in the habit of checking your online accounts regularly to make sure that there isn't anything funny going on with them (charges you didn't make, emails you didn't send, etc.) and changing the password frequently, as new security flaws will always be discovered. I know that that is always easier said than done!