I'm glad I'm not the only one who does that from time to time. I've even got "lost" on easy songs...and I almost always have music in front of me, and still it happens. My wife says she never notices it, so somehow I fake my way out of it. I always cracked it up to how we play something different every week with one run-through on Wed and another on Sun morning. Generally it's a couple months before we do a song again at the earliest, with it generally being a number of months if not a year or more. I hate that part. I liked a band setting much better because you keep going over songs until they are second nature....and when it's show time you don't have to think so much about it. I think learning songs without music was a help for me as well. For what I'm doing at church with different songs every week I gave up trying to memorize songs long ago. No point since you may not play that song for no telling how many months or even years....or ever.