Am I actually playing against a 1425 rated player? I am using Deep Shredder 13 and somewhat struggled with the engine at 1400. I then managed to defeat 1425 with great ease. The game went as follows

[FEN ""]    
    1. d4   e6
        2. Bf4  Nf6 
        3. Nf3  d6 
        4. Nc3  h6  
        5. e4   g5
        6. Bg3  d5 
        7. e5   Ne4  
        8. Qd3  f5 
        9. h4   Nd7  
        10. hxg5  Nxg5  
        11. Nxg5  Qxg5 
        12. f4    Qg8 
        13. O-O-O h5 
        14. Bh4  Bh6 
        15. g3   Qf7 
        16. Nb5  Nf8 
        17. Qc3  Rg8  
        18. Nxc7+  Kd7 
        19. Nxa8 Qh7  
        20. Qc7+ Ke8 
        21. Qd8+ Kf7 
        22. Qe7+ Kg6
        23. Qf6# 


Thus, this brings me to question whether I am actually playing against a 1425 rating. On my iphone app I struggle with a 1350, thus I am unsure what to make of this. During the game, I saw obvious threats (Nb5xc7+) which could've been avoided. The engine instead of avoiding mate with Qxc7, it went for the dubious move Kd7. Afterwards, when I added a new variation, it actually went with Qxc7. Why does this occur? I mean it seems as if I was playing against a 1300 rating. What is the logic behind this? (Also, I should add that during the game the engine was limited to book knowledge)
I don't know if the engine was really playing at 1400+, but it was quite weak. 1400+ rating sounds fair to me.

Please note:


Shredder is not the iPhone app you mention. It's rating system is not the same as what Shredder is using.
The iOS app you mention is definitely under-rated. I tried it several times, I know.