Help - advice on frame needed

I have just bought this frame and while it does look pretty sweet there is a slight cut/crack just where the seat lug joins the seat tube - see the photos (yeah yeah, photography fail...).

http://i910.photobucket.com/albums/ac307/gavmon2008/DSC_0039.jpg
http://i910.photobucket.com/albums/ac307/gavmon2008/DSC_0038.jpg
http://i910.photobucket.com/albums/ac307/gavmon2008/DSC_0034.jpg
http://i910.photobucket.com/albums/ac307/gavmon2008/DSC_0036.jpg

There is also a little swelling in the area (difficult to see in the photos) and I'm wondering if maybe the seatpost corroded inside it and pushed the tubing out? There is however no corrosion in the seattube itself.

Sooo, what I really want to know is will it get any worse? Should I ride it as is or should I take it to someone to file a nice little keyhole to stop it cracking any further.

Also, should this have been mentioned in the sale ad? There is a small dent in the top tube and 2 tiny dents in the right seat stay as well. Neither the crack or dents were mentioned, and the affected parts were not in the sale photos...

Cheers

erm, it does look like trouble to me, and i'd probably want to get sorted before i rode it.

I'd just send it back to be honest if it wasnt mentioned, you'll end up worrying about it.

erm, it does look like trouble to me, and i'd probably want to get sorted before i rode it.

I'd just send it back to be honest if it wasnt mentioned, you'll end up worrying about it.

Thats what I thought. I'm really pissed though as I like the frame!