I wouldn't worry until I refilled the oil and tried out the engine. A few months ago, after I had my oil changed in my car, the filter gasket sprung a big leak, and basically spewed all the oil out of my engine while I was driving, and since it was night, I couldn't see it happening. I probably drove at least one mile with no oil remaining, and the red light was starting to flicker when I pulled into my garage. I had the servicing shop replace the filter and refill the oil, and my car has run fine since then.