Alright, so I took the post off to have a good look.
AND.............



There isn't any crack. The 'crack' in the back is the result of an uneveness caused by the cut of the seat tube. Aka, it wasn't cut perfectly so the top surface isn't smooth. Instead it dips down at one spot, since it's a very sudden drop it looks like a crack (think plateau).

The other thing is similar as well. It's not cut smooth so there's a lump on top of the tube.

Shouldn't be an issue. Silly light playing a trick on me. Silly cannondale not cutting things smoothly. Silly me...

I'm probably driving by the shop where I bought the bike in the next week or so. I'll show it to them.

I couldn't see anything wrong either on either side of the tube (inside or outside) which I think would happen if there was a crack. I don't think the shop is going to be worried about it at all. I'm not worried about it anymore either. I'll just keep an eye on it and show it to them 'just in case'.