Interesting, thanks guys. I dont think it was a reaction to yeast, I have in the past had beers made from dry yeast where the bottle got mixed up, I drank the yeast, and it did nothing. Also it felt like a gluten reaction, albeit "the mildest glutening ever" - but it had most of the usual signs. Usually I put the beer in the freezer for 1hr, and pour gradually, but this time I was at my parents place, and the bottles fell off the seat and were jostled due to my driving.
Although, I am very sensitive to gluten. There were 2 posts about the PPM level, one was 120PPM, and one was 2?! - I dont think i would react to 2PPM! There could be a variation in the ppm batch to batch also, and this was a half-sized batch (2.5gal) so that could have doubled the final PPM. In some places, like Australia, the limit is 5ppm.
But I think I am going to keep using smack packs this way, and either do another racking, filter them through 1micron filters & force carb/keg, start yeast washing, or I could do regular/double-sized batches (to dilute it). Overall, I "think" there was between 50-200PPM of gluten/peptides on the yeast, but I cant prove it... other than drinking a mixed one - i'll do that right now.
Had one that was mixed up, and I could sense a bit of a reaction, but not much. Probably takes 2+ 500ml shaken beers to cause a reaction, so maybe I dont need to do anything to a 5gallon batch. This is probably a rare situation... well, at least this is out there on the internet - be careful with liquid yeasts.