I too went to the trouble of flying to a non-E.U. country - Switzerland - as to get my passport stamped for any problems last year. I was teaching English at the time so I was worried, but afterwards I realized I could have stayed a lot longer and no one would have cared. They don't seem to care at the customs gate unless you look like someone you're profiling. I've gotten the impression that as long as you're a person with money to spend in Spain, you are welcomed with open arms. It's a pretty 'laissez-faire' attitude.
I had good friends to visit in Switzerland anyway, so it wasn't a waste, but I wouldn't worry about it now. The worst they do I guess is tell you that you have to leave. So you go and come back I guess. Whatever.