I doubt it's just me, but what determines whether you get to "slide to answer" a call or tap "accept" or "Decline"? Is it arbitrary? I haven't been able to figure out a rhyme or reason for this.
Ive noticed if the phone is "asleep" when the call comes in....then its a "slide".
If your using the phone in any way (playing games, email, internet, whatever) then it gives you the "tap" options because you then have the ability to decline the call and continue what your doing.