This is a heads up to check your timer every so often, if you have one.
We have the Intermatic T101R, set with two screw-on tabs, one to turn it on, the other to turn it off. One of these tabs tends to work itself loose, probably from the physical vibration when the timer sets itself and the times when I set it manually during its off-hours. When it loosens it rides at the 6 0'clock position on the clock wheel, by gravity. Obviously, the pump can't come on that way.
I'm hesitant to put any sort of locking compound on it because I may want to change its setting now and then. I just check it every other day to make sure it's still in place and tighten it, if necessary.
Here is an example of a perfectly simple equipment malfunction which could present you with a 'green' surprise upon return from vacation.