EHM The Blue Line

I've noticed this two times now and wonder if there is a real world explanation. Here's the setup..

I've set the lines for my team but leave the coaching and in game tactics to the head coach. I GM the Bruins and two times
I've had Thomas in goal and he went to the bench and an extra player came on the ice. Once in the first period only 8 minutes into the game and once in the third period with a one goal lead and more than 10 minutes remaining in the game.

I'm wondering if this could be a bug in the AI coaching the game for me (I've never seen the AI do this)? Or is there another explanation? The only thing I could think of is if the goalie broke his stick? Would he have to move to the bench to get another or can a skater get one for him? In the pbp there is no mention of him leaving the ice or why, but it does announce that "Thomas returns to the net".

Is there another real life explanation or has anyone else seen this?

I hanven't posted this at the SI boards but will if nobody here has an explanation.

Delayed penalty on opposing team? Just a guess. Probably too simple a guess, but a guess.

I'd have thought it would be a delayed penalty too. Shortly after the goalie goes to the bench is a penalty called?

Thanks for the replies, I'll check out the possible delayed penalty call.

That is definantly a delayed penalty.