6 weeks and doing what????

So last night Ethan and I were laying on the floor for "tummy time". He loves being on his tummy and both Jeff and I lay down with him for this fun time. Last night, Jeff ran to get some dinner, so it was just Ethan and I. The little stinker ROLLED OVER!!!! At first, I thought I had imagined it and put him back on his tummy. Then he did it again! I was crushed! So I waited for Jeff to get him - just to make sure I wasn't losing my mind. He did it again. Jeff was shocked. At that point I decided enough was enough and there would be no more of that. He is NOT supposed to roll over so quickly. He's been trying for a couple of weeks. Kim was playing with him one day a couple of weeks ago and noticed, but she said surely not for a few months. Why is time passing by so quickly?