It's not Three Towns telling you: it's your browser. This has happened fairly recently with the advent of greater security options built into browsers and the trend towards everyone using https://. In reality the site is as secure as it's ever been and the notification you're getting only applies if you were storing confidential information. Being a public forum that anyone can use, advice remains the same: be careful what you post, don't reveal personal information and never disclose your passwords.
Your password, incidentally, is encrypted, so even we can't locate it, but the database itself is plain text, so anyone feeling sufficiently masochistic could download it (if they had access, which only Dave and I have) and plough through the massive amounts of text therein.
You can override the browser by going to tools / settings or going into the preferences. In short, I wouldn't worry about it.