I don't have connectivity to my IPhone right now so I can't experiment with it.
Go to the Foreflight site and log a tech support request. They almost always return an answer within 10 minutes. Their online support is unbelievably good.
I noticed the same on my iPad. Intuitively, I would think that tapping on the PIREP would expand it, but that doesn't seem to work. I haven't had a chance to contact ForeFlight support, but if you do, please post your findings.