Just had it done to me. 60K points stolen from my account and only returned after I called and complained. Watch your points balance folks. I specifically asked if I hadn't called if they would have eventually credited the 60K points and they said no. What happened in my case:

• Booked in July a hotel for 340K points.
• Today I receive the reservation confirmation email *again*, which I find odd so I read over the entire email. Notice it says 400K points which is different than the original reservation confirmation email received in July.
• Login to my account and it shows:
July: -340K points (original booking)
Today: +340K points AND -400K points

Note I did NOTHING with the reservation. Didn't change anything – hadn't even logged into my account and they did this. I wonder how many people they do this to that don't catch it? Maybe it is just an IT problem, but sure is convenient for Marriott that it results in stealing points from customers.