It seams to be a software issue, since even if you go to edit the lock screen and you don't edit anything, it will drop. I hope they fix it, for now I just put in there, instead of the phone, the "Call History" since it will take you almost in the same place. You can find the "call history" in the menu list when you go and edit the lock screen.
Another issue I had, was the weather lock screen, in Las Vegas we have many days with temps over 100, and the one on the temp is always outside the screen, yesterday it was 109 and if you didn't realize it, you would think it was 09 degrees in here lol. It seams who wrote the code forgot to calibrate the 3 digit temp display, I think they should've had the temp in the middle on top of the city name, just my opinion.
I'm very impressed with the fixes that Sprint is rolling out, very fast fix. THX