No, probably not. Grass-fed beef (assuming that's what you got) tastes different from the regular grain-fed stuff. I think it's worth buying, too.
There is no definitive proof that the antibiotics and hormones used in meat processing are harmful—hormones, after all, are naturally occurring substances—but if you want to play it safe and can afford it, it certainly can't hurt. (NOTE: I'm not sure about Canada, but in the US, "no antibiotics" on chicken is misleading as chickens meant for eating aren't allowed to be treated with antibiotics.)