Question About Brake Warning Light on 2002

Hi all -

I purchased a used 2002 Prius about two weeks ago. The car was in excellent condition, with about 65000 miles. I am very pleased with my purchase, but over the weekend something I consider strange happened more than once.

When driving, the brake warning light came on for a second or two, and then went off. I immediately stopped and pulled out my owner's manual, which states something to the effect of "the brake light coming on intermittently is not a cause for concern." I have checked the brake fluid level, and it is fine.

My question is: do I trust the manual that this is normal? I know the Prius has regenerative braking, but I really don't understand what that means. So I thought I'd come ask the experts for your opinion about this since the dealership is closed.

Linda