check the reciver plate on the door frame , were the latch goes in , as you lift the handel, the silver plate on the door frame that takes the lock/bolts it could have moven up or down a little, mark the latch with a marker , and see if it puts it mark on the silver plate , if so you have to ajust the plate up or down as needed, till there is no mark , and it locks as normal..
mick, May 2008