Hi pigeon 3♥. As a passed hand couldn´t be a reverse :) My guess is pard had an opening balanced hand with Diamonds and decided to pass at his 1st turn. 2NT is a weary and good bid, because you could have bid 2 Clubs with less then your good 11 pts. So, nothing to lose bidding 3Hearts "en route" to 3NT, trying to catch a possible Heart fit.