I have 09 ranger, 4wd, v6.
The door lock on driver side after unlocking with the key, will relock as I lift the handle, I cant see what is going on inside as to the relocking( I did take off the door skin and looked inside) ... but now its really getting on my nerves. Im having to carry a spare key encase I exit while the key is in the ignition and the door closes by chance...
I have a viper keyless entry door locking thing... Im not sure if anything to with this issue but mentioning anyways. It also stopped working a little while ago, well the unlock/lock mechanical function. The electronic alarm with the door opening will signal the alarm as usual.

 

Finally moved switch , NO more bumping it while pulling handle to exit truck.