I reported a bug in-game today, which seems to have been introduced with patch 5.1. You may "feel" this if you compete in the Stranglethorn Fishing Extravaganza, which is returning this Sunday, 2-Dec-2012, as part of patch 5.1:
When fishing, the first cast works properly – there is a fishing line visible between the tip of the fishing pole and the bobber. However, for all subsequent re-casts, there is no fishing line - just a bobber, floating unattached to the pole.
This problem is "reset" by moving, catching something, mounting, etc. - it seems that performing any action (other than re-casting your fishing line) will reset things such that your next cast will have a fishing line - but just for the first cast.
This is particularly annoying when fishing from pools, when anglers will frequently want to re-cast, to get their bobber to land inside the pool. Because there is a slight delay in the in-game animation, from the time you cast, to the time the bobber appears in the water, you have to wait for an extra heart-beat on every re-cast. The process went faster when the fishing line was visible on every cast, because the line appears faster than the bobber.
I tried adjusting my system's graphics settings, but even with everything set to "Low" in the in-game System Settings for graphics, this "vanishing fishing line" still happens consistently on all re-casts.
So, it may take just a bit longer to catch those 40x Speckled Tastyfish, but I suppose this bug will affect all anglers equally, right? Are you also experiencing this bug?