So, what MWB was probably blocking was an infected Ad on one of the pages. I can't say for certain, but it should tell you somewhere what address was blocked. If it's some janky looking thing, it was probably an Ad.
It appears that MalwareBytes is "not ready for PrimeTime" in this respect. I turned this feature off. The reason I did so is that MalwareBytes bases it's decision upon the IP address alone. This is inappropriate since most websites use shared hosting which means that both good and bad websites will share the same IP address. MalwareBytes definitely got it wrong here. You can't potentially block nearly half the internet because they use shared hosting. That's like using a sledgehammer on a thumbtack.