Reset For Phone Via Battery Removal ?

Hello,

Have had a Samsung a650 cel phone, with Verizon service, for a year or so
now.
Has always worked very well.

Today, for the first time ever, the screen lit up just fine when the cover
was opened, but couldn't send, receive, or access any messages that were left.

The battery indicator showed a full charge.

Past experience with other gadgets has shown that sometimes plugging and
unplug the gadget works to reset things, when there is a problem.

So, for the heck of it, I took out the batteries, replaced them, and now
everything works just fine, like always.

So, can anyone explain what might have happened, please ?
Just would like to learn a bit about this.
Trying to call Verizon service to ask is hopeless.

Is this a common cel-phone phenomena ?

Thanks,
Bob