Houston, we have a problem: Lady Gaga took a nasty spill during a concert there as part of her Monster’s Ball tour the other night. The mishap occurred while Gaga was doing the splits on a piano, straddling the keys and bench, when she slipped and landed flat on her back. But to her credit, Gaga never missed a note of “You & I,” calmly got up and carried on like nothing happened. A YouTube clip of her tumble drew more than 84,000 views by early yesterday evening. Maybe Gaga has a balance problem — YouTube is littered with other videos of her falling onstage.