I have made this 5 g batch many times in 6 years. This one was an extract . Everything was clean and soaked in Idophor. After fermintation and FG was taken I kegged and noticed the yeast was curdled ( looked a bit like cottage cheese). The beer taste was different , not good. I expect there was contamination somewhere , but wondered if this freashly bought vial of WY001 could have been bad.
First off, sounds like you are talking about WLP001 (White Labs), not WY001 (Wyeast). Just trying to get a hand on what strain you are talking about.
Yeast doesn’t really “curdle”, it does flocculate (clump together). WLP001 doesn’t flocculate very well usually. B ut it would not be uncommon for it to show characteristics of flocculation. WLP002 is very flocculative and often looks like this.