I am getting the feeling from a few recent games that a knight can be harder to contain than a bishop in an endgame. Is it really position dependent?

Edit: That is I find it harder to stop my opponents  knight than a bishop.

Your on the right path there. Knites are harder to "dominate" than bishops but as you said their usefulness is dependent on the type of position.- Knites are favored in closed positions and positions where there are pawns are only on one side of the board (in endgames). Bishops are favored in open positions and where there are pawns both on the kingside and queen side. Also if you still have a rook on the board it is worth noting that bishops and rooks "get along better" (are a better combination) than knite and rook. The opposite is true of queens and bishops and queens and knites- you want the knite and queen pair instead of the bishop and queen, they work better together. So as you can see Knites and bishops are very temperamental pieces and their power depends in alot on the dynamic of the position that has arisen over the board. Hope this helps.

Bishops can easily dominate knights especially in an endgame.

Here's a recent game of mine where I won with 2Bv2N in a semi closed position.