You can set your Twitter account to always use https; i.e., a full-time secure, encrypted connection. You should do this anyway, because why not? But especially if you access Twitter from public Wi-Fi hotspots, or using one of those smart phones (?) I keep hearing the kids talk about. (You remember this issue, in the Facebook context, probably.)
Go to your Twitter home page, click the Settings link at the top of the page, scroll down to the bottom, tick the box marked "Always use HTTPS," and click the Save button. Done. (You may get asked to type in your password again. But then you're really done.)
More info from the Naked Security blog, if you want it.