Oh yeah! That's what I'm looking for. So. Did some digging again, I think you might be onto something with the formula change in the lid manufacturing. I tried some other Nalgene lids, one of which had an integrated straw and small-mouth cap, and the other had a flippy ring/cover (which could break rendering your bottle useless but that's besides the point)-- and both fit the Guyot perfectly flush. It seems the basic no frills Nalgene wide-mouth lid is the change here, perhaps not the Guyot bottle. Furthermore, I think it is the thread pattern on the inside of the Nalgene wide-mouth basic cap itself, not the thread pattern on the outside of the Nalgene wide-mouth bottle. Baffles the mind. Now I feel like a first-class @sshat for complaining to the Guyot people. Ah well, you live and you learn.