I've brewed my first two BIAB recipes and both have a strange flavor in them. One taster described it as having the aftertaste of formaldehyde. The first one was Northern Brewer's Cream Ale recipe with Wy1056. I had a long lag phase (2 days) and I attributed my off flavor (astringent) to that. Now it has shown up in my second BIAB attempt, BM's Centennial Blonde (brewed with Wy1450). The Blonde had a shorter lag time, about 6 hours so that is not the culprit. The only thing they have in common is that both used the same base malt, canadian 2 row, and both were mashed low, I mashed in and walked away.
Any ideas where this flavor may come from?