Door Locking Issue

I recently replaced the battery in my key fob - just as a preventive maintenance measure. All worked fine for the first couple days.
Now, when exiting the car I push down on the door lock inside the door, get out and the doors unlock immediately. Only way to lock the car is to press the lock symbol on the fob. Touching the handle no longer works to open it. I must use the fob. The button beneath the steering column is in the correct position. Any ideas? Thanks, all!

 

No 2nd fob available currently as I'm in the hospital with my wife, who was falsely diagnosed with a heart attack but all is well.
I will experiment with your advice first chance I get. I Thank You!

 

Mystery solved! In our panic to get to the ER, I put my wife's purse in the trunk - WITH HER FOB in it. Everything functions as it should upon it's removal from the car.
But, while I have you on the line, I would appreciate some of your wisdom. I've driven my Prius now for nearly 2 years and am happy to report that I have come a long ways in my understanding of its operation. P & G is a breeze (I can even glide at around 50 mph - no arrows) and am managing about 53 mpg average, not counting winter. I drive exclusively on rural state and county highways - no chance to P & G. frequently. It is only a 6 mile commute on a fairly busy highway. The one thing I still have not come to grips on, is how to accelerate for best FE. Slowly to 55 mph, quickly to 55 mph, pedal to the metal or what? I've read numerous opinions about this but would like to know what the general consensus is regarding acceleration. BTW, thank you for the kind words re: my wife's health. We are finally home and she is getting some good rest. Lots of interruptions when in a hospital! Just the same, God bless the nurses of this world.

 

Thank You!