Just did a transfer last year. Left previous group

for I couldn't stand with my former manager any more.  The transfer was smooth.  The thing was while I had many chances to bad mouth my former manager I didn't. In fact, his manager talked to me many times trying to keep me, I kept my political correct reasons.  The former manager knew this himself.  He didn't say anything inappropriate I believe.  However if he did, his life wouldn't be pretty either. HR, his manager would all know what happened.