Just means the aging process just finished. Ammonia is one of the things that is produced by tobacco as it breaks down at certain stages. When you run into this let it air out. Oh and let the pipe air out. The tobacco literally should take a few hours at most the pipe a few days.I'm openly new to pipe smoking, having only started a few months ago. In that time I've been mostly smoking English and Balkan blends, and enjoying them very much.
Recently been dabbling in some light aromatics and Virginias though for variation.
Very recently I've purchased some peterson's Connoisseur's choice and some macbaren navy flake. Both of which (moreso in the peterson's, which has ammonia ghosted a cob ) have displayed an ammonia scent/flavour in the last 1/4 of the bowl. I've not had the same with some peterson's Flake (for context).
Am I doing something wrong or have I accidentally stumbled on two consecutive 'dodgy' tobaccos?
Its not a pleasant scent at all.
But the important thing not a big deal and nothing to do with how you've done anything.