Yes, you will have trapezoidal image if no corrections are made. Digital keystone correction will be scaling the image, resulting in potential loss of sharpness and occasional visual artifacting (often not noticeable, depends on how picky you are).
Sounds like the amount will be pretty slight though -- the lens centerpoint is about 3" below the top (when ceiling mounting) on that projector if I remember correctly, and the offset will be about 5-6 inches. So the 'best' location for your screen would be around 8-9" below the ceiling. Your screen is 24" below the ceiling, so 15" too low.
Now, you've got 113" throw distance, and your error is 15", so that's tan^-1(15/133) = ~7.5*
So assuming you won't return the projector you have 5 options:
-Trapezoidal display area
-raise your screen 15"
-lower your projector 15"
-Angle your screen to match the projector angle. Basically, if you move the bottom of your screen out away from the wall about 6-1/2", your screen will now match the angle of the projector. There's still a suboptimal viewing experience since the screen will not be perpendicular to the viewers, but I personally did this once and found the result OK. I think in my case it was about 6* (compared to your 7.5*) and I could definitely tell there was a tilt, but it never really bothered me. This is a subjective thing, however, so ymmv.
*EDIT* actually less than 6-1/2", even if you've got a flush mount, there will be some drop from the ceiling, probably another 5" or so. So you're probably more like 10" too low instead of 15" --- which would be closer to 6* angle, which would need more like 4-3/8" spacing from the wall on the bottom.
Math behind this is pretty simple, basically the ratio of the offset "error" to the distance you're projecting should equal the ratio of the bottom spacers to the total screen height.
In other words, if there's 10" error, E/113 == X/49 where E = error and X = screen bottom spacing. So if E = 10, (10/113)*49=4.33628..... (around 4-3/8)
The error is how far below "perfect" your screen is.