Weird inputs or game mechanics?

So I have a weird issue. I am not super good at SSF4 but I have noticed a weird issue. When playing Shoto in SSF4 and I am footsie'ing back and forth and then i throw out a c. mk I into a buffered fireball I notice if I do it super quick I get a c. mk then DP. I think I have narrowed it down to the SSF4 DP shortcut of 3 2 3 (F, DF, F).

This just seemed to start happening.

The reason I am posting this in to Tech Talk is because all I have to test it on is PS360+ so I am hoping some Tech Talk \ SSF4 player can help me out and tell me if it's the game or the PCB.

Thanks!!!!