I think Bitcoin fees have reduced recently. Is it due to Segwit?
Nope. I think most of the transactions were stuck last time and thats what caused the increased in the fees so that people wont transact more and the miners will get rest on processing the transactions that already in the pending list. After this event recently, mempool was able to release most of the transaction leaving behind only 150k transaction in the pool to be confirmed and thus losing after the relaxed mode the prices came down. Thats the real reason behind the increased prices and now that is the reason for its drop down.