Norton warns but avast not

A friend informed me this morning that he got an malicious iframe image request from my blog (catatan.legawa.com) when viewing on of my post. He use Norton, and here is the report:

http://img507.imageshack.us/img507/6963/maliciousframefromlegaw.jpg

But avast doesn’t give me any warning, how could I know whether its real threat or not?

A chech on the site shows nothing that should be reported ??? Update his Norton and rescan - 8)
This site is good (0)
This site spams (0)
Adware, spyware, or viruses (0)
Excessive popups (0)
Phishing or other scams (0)
Bad shopping experience (0)
Browser exploit (0)

Looks like it is a false positive by Norton
http://www.virustotal.com/url-scan/report.html?id=e1230a274de984da4295279bb85f9344-1293681817