Question about pitching dead yeast

Hey Guys, A friend and I recently brewed a Belgium blonde triple (all grain, 6 gallons) and my buddy gave me a masson jar (1/2 full) of some wyeast 1388 he had harvested and saved from a previous batch. I pitched the yeast and after waiting a few days I realized it was dead (not signs of krausen or air lock activity). So, I pitched some T-58 and my brew is happy bubbling away now. My question is, will there be any side effects from pitching such a large amount of dead yeast into my brew (off flavours)? Thanks

You may get some of the autolysis flavors if it was really old and the yeast cell's released all of their guts. How old was the yeast?

More than likely though, your live yeast will use some of the dead yeast as nutrient.

Yeast wasn't very old but it was probably on it's third or 4th harvest. Been in the fridge only a couple of months max.

Or, even more likely, the yeast wasn't dead at all- just inactive from being stored. With stored yeast, it's good to make a starter to get it going again and "wake it up". It probably got going again in the beer, that's why you're getting activity.