What is this and should I be worried?

[xlayedoutx]

I noticed this tonight as I filled up my tank to check for leaks. I'm not sure if it was there before I added the water, and I'm not even sure what it is. It looks like its between where the two pieces of glass meet. I never noticed this on my 75g when I had it but then again I don't think I really paid attention.

http://www.cvreefers.org/attachment.php?attachmentid=7469&stc=1&d=1199247157

http://www.cvreefers.org/attachment.php?attachmentid=7470&stc=1&d=1199247157

[landlord]

It looks like it could be reflections from imperfections in the cut surface of the glass.

Tough to tell though. FWIW --landlord