Sudden Sour Taste?

I've been trying out different tobacco samples. I got to one that I know didn't get great reviews, but hey, why not try it? "McClelland McTruffle". It started ok, but about half way through, the flavor started getting weak and I started noticing a sour taste. I couldn't tell where it was coming from until I touched my tongue to the stem - the moisture accumulating inside was SOUR.
It's just a cheap Missouri Meerschaum hardwood, but it has never had a hint of off taste with any other tobacco. And it seems like I have a very mild sour taste in my mouth now. I'm not even going to finish this bowl. Once it cools down, I'm going to clear this stuff out.
What the heck happened? I clean my pipes after every use and this seems like it's the tobacco itself. It's on the moist side, but seemed to burn fine with no relights or constant puffing.
Thanks

Wow..now my pipe smells like BBQ sauce!!
That was the first truly lousy smoke I've ever had. After 5 or 6 years.
If I didn't know better, I'd think maybe I was burning the the pipe, tasting the wood itself? But I was hardly getting it warm and it has a "good enough" cake.

I can be a somewhat wet smoker at times, but I've never tasted anything this horrible. Not even close. Do some tobaccos produce particularly nasty juice? I'm reluctant to give this stuff a 2nd shot. At least it was in an $8 pipe and not a briar.

The strange part is that particular tobacco just kept tasting horrible. I *did* run a soft pipe cleaner through, but the damage was done. The rancid tinge stayed in my mouth after a drink - it took a solid toothbrushing to diminish it. And the pipe still smells rank. I'll certainly give the tobacco a chance to dry out if I decide to give it another chance.
For many reasons, this particular tobacco is at the bottom of my list. I have a couple hits in this round of samples, and, "McTruffle" ain't one of them. Oddly, this tobacco and all the 700 series McClelland tobaccos I've tried have a musty quality to them. The 400's are entirely different, like they were conceived and mixed by a vastly different entity.
Going forward, if I load up a questionable tobacco into one of my Missouri Meerschaums, I'm going to stick a filter in. I'll probably toss the "skanked" hardwood and replace it with a couple more cobbs - they seem to tame sticky crap better.
Thanks.