Mushrooms taste FUNKY
There are three possibilities:


Your mushrooms were bad, if they are a bit off the result isn't likely to be good
Your choice of mushroom was different, with a different flavor
Olive oil burns on high heat, creating off flavors. My money would be on this being your problem. Next time reduce the heat a bit if you want to use olive oil, or use a higher temperature oil like canola (rapeseed). You could also try a bit of water or stock, steak juices are mostly water, not fat, and that would reproduce the conditions of the pan more closely