Keypad occasionally doesn't 'ding' to remind me to disable the system

Randomly our keypad will not chime when you walk in the door, thus I may not remember to turn the system off. The keypad senses the door sensor opening if I look at the screen, the base station logs the messages of the entry, the timeout... etc. we just don't get the chime. When the alarm goes off I can silence by entering the code on the keypad so it is talking with the base. The base is only about 35' from the keypad.

This happens once or twice every couple weeks, we have swapped out the keypad, moved it, moved the base, still randomly happens.

Anyone else see this?