What causes a TOB to fail?
 

Hello HT folks,
last week while on my way home from work my 97 Accord started making what I initially thought was belt squeal but soon realized it was a) dependant on whether I was pushing in the clutch pedal or not and b) sounded more like screeching not squealing. I was almost home so I just babied it the rest of the way. When I pulled in my driveway, I pushed the clutch in and out a couple times to confirm it was dependent on that, and it definitely was. I turned the car off, popped the hood and saw smoke coming from the slave boot. Well I did some reading up to refresh my memory and found it was probably my throw out bearing. Ordered a new clutch kit with the express delivery and started on the task of dropping the trans while I waited for my parts. A few hours later this is the state I found the TOB in when I got in there-
https://cimg1.ibsrv.net/gimg/honda-t...436982869.jpeg
https://cimg2.ibsrv.net/gimg/honda-t...f1b0b621b.jpeg

​​Best I can tell the seal that keeps the grease inside failed and completely cooked itself. Thankfully nothing else is damaged as far as I can tell. My question to all you good folks is what would cause this? I do have the habit of keeping it in 1st gear at stoplights but this seemed to be a very sudden event, not gradual wear. Anybody have any ideas? Thanks in advance