I've noticed this and am a little suspicious myself, but you also have to take into account that Ethereum and crypto in general has had a lot of new people join in. That means that places like Coinbase, Poloniex, and other exchanges are experiencing more traffic than usual. That means that these places have to scale up in order to deal with all the traffic. However, it seems like Coinbase in particular has been the slowest to scale up... I'm not sure what to think, but I'll give these exchanges the benefit of the doubt until they give me a solid reason not to.