If the blade was singing while you stropped it, you may have rolled the edge. If you have a pasted strop you could pass it on it, but if you get that angle off you will grind the edge off the blade. If it is rolled, a hone touchup is in order. It is easy to roll the edge, I still do it now and then. There are a lot of factors to work at once. You have to hold the razor correctly, hold the strop correctly, hole enough pressure on the strop to keep it taunt without ripping it off the wall all while passing the razor down the strop in the correct direction (no side to side sliding) while using the correct pressure on the razor to strop (next to nothing) and keeping the blade flat on the leather. If it makes any kind of rasping/scraping sound then something is off. Put your hand on one of your kitchen cabinets, then gently slide it across. It should make a very gentle sssssssss sound. Your stropping should sound similar, quiet and gentle.