Sorry about the "challenging" question. I tend to be the type of person who tends to "push things to the edge" without even knowing it. In my software test profession, people say that "bugs just fall off my screen". Often, I find these sorts of problems through a combination of luck and dilligent, persistent observation. That was the case here. During the first few days the GUI became"slow" like this (and I wasn't able to dismiss cards similarly to what I described this morning), but I didn't have enough "observation time" to yet correlate this to a busy (possibly overheated) CPU. Last night, I pushed it pretty hard and was able to make the correlation. I really didn't expect an answer from you, but I was hoping to share what I found so far in case you were able to "chase this up the ladder". I'll share a trick that should be able to make it easier to reproduce: if you were to wrap the phone in an insulating material (such as a dish towel or a sweater), you could get the device to heat up a lot faster. Mind you, I don't want to do this to a Pre, but if you get some returns that are going back to Palm anyway, a little "cooking" in the name of science might be something you could get away with. (I learned this trick by accident on a Palm Treo 700p.) The 700p seems to have a thermal cutoff (or just device characteristics) in the screen that shuts off the backlight in an overheat situation.
I do believe in doing controlled stress tests just so I know what the boundaries of my phone are (so I can prevent accidentally crossing the boundaries). I think the Pre's overheat protection scenario is to scale down the speed of the CPU. (There is a discussion on this board you could read.) I really just wanted to point out to you and your peers in the trenches at Sprint, that when a customer complains about a slow GUI, it might be because they are taxing the device a bit too much. I think Palm separately accounted for some heat while charging the device, and some heat from "taxing" CPU operations (such as playing Pandora or an itunes stream), but they didn't design for the case of a user doing both at once for an extended period of time.
So once again, I hope these ideas can help you to figure out what the real tolerances are (across several devices that wind up on your repair table). If you can share any practical wisedom back our way, that would even be better!
Regarding the advice on the bleeding screen, thanks - I'll try and get to a store soon so I can hopefully get a good replacement before the 30 day period ends (as you say, to avoid the hassle).
thanks, -- Bob