I think this probably happens more times than people would like to admit whether intentional or accidental. I think we have all seen the clock freeze for a second or two, or keep running for a few seconds after the whistle before.
Not NHL, but just the other day I was watching a Walleye game on TV, and there was only a minute or so left in the period the Walleye were srtuggling to maintain their lead, and even get the puck out of their zone, and when the whistle blew the clock stopped, then ran again, then stopped for a millisecond then ran some more before it atually stopped. It was probably 10 seconds that ran off.
Edited by sleepwalker, 02 February 2012 - 05:33 PM.