I have had this happen a couple of times. This is an IPA extract kit from Craft-A-Brew. I brewed it a few times over the last year before moving onto BIAB. The first time this happened I thought it was just a one off and didn't really take much notice, but now this has happened a second time. The beer on the left (hazy) is how the beer normally looks, but the clear beer on the right is the one-off (from same batch). Over the past year I have probably made 200 bottles of this beer and just two bottles have been totally clear. Beer tastes fine by the way. What might cause this?