The pictures do make it look like it's sitting at an angle somewhat. When I put the form in the hole, I use a level on all side and made sure it was leveled before calling in the concrete.
I could not afford to fill the whole form, and took whatever lumber I had laying in the backyard to make the form... To level the concrete I used the 2X6 that's currently sitting on top of it all. Me on one side, my girlfriend on the other and slid the peice of lumber from one end to the other. The left side of the slab is currently grass, but it will soon be dug out and be replaced with crushed stone flat against the slab to hopefuly counter water infiltration.
To give a perspective on thickness... The left and right side lumber are 2X6, the front and back peices are 2X8. I seem to have approx the same distance from the concrete to the edge of the wood peice on the whole length, which was my "guide" for leveling the concrete lol
It was poured sunday afternoon, am I safe to remove the form tonight?