Penny Lancaster, 53, has shared a gushing tribute to her husband Sir Rod Stewart, 79, and fellow musician Billy Joel, 75, following a joint gig the two played together. In what was a memorable milestone in the Maggie May rocker’s career, it marked the first time the duo had ever performed with one another – despite both spending decades in the spotlight. Stewart joined the Piano Man singer on stage at his gig on Friday at Huntington Bank Field, Cleveland, Ohio – home of the NFL team, the Cleveland Browns. The 67,000+ seater stadium looked packed to the brim as the two legendary musicians perfo…