Play counts and penalty yardage added?

I seen this happen several times now and it bothers me. A prime example happened in OT of the Denver/Seattle game.
On a play Wilson scrambled for a nice gain - there was a flag thrown for one of the newer ticky-tack calls (illegal contact or defensive holding or something like that) away from they play. The refs gave Seattle the yardage on the play and tacked the penalty yards on afterward.

What ever happened to you decline the penalty and take the play or you take the penalty?

This seems to always benefit an offense. I have seen offensive holding occur and the defense stills gets a sack - you never see the penalty for the hold tacked onto the end of the play - you take the penalty and reset the down.

What is the deal with the play I described above from the other game????? Is this actually correct or did the refs make up some new stuff?

 

situations where penalties are not marked off from previous spot

1) offensive penalty occurs after yards were gained - back from where the ball was when when the foul occurred
2) personal foul on defense - added to end of the play
3) dead ball foul - forward/back from new spot

only ones I know of - doesn't sound like what you described though

 

Thanks for the reply. I wish someone (like one of those talking heads on tv) would address this.