never left any of the LMF plastic ones in the pot when cooking (gets used and then back in pocket for brewups and food stealin') and they have all went at the same place. I think its more of a weakspot in the design / choice of plastic rather than user abuse Goatboy imho.
However now I have a Ti one I should have no further problems and because its Ti it should make me lose 5st, be better in bed and my life should improve immeasurably - failing that at least it wont melt