My ring fingers have always been longer than my index fingers.
I've heard of this before, but I don't really pay much attention to it. I'm not sure it's an indication of being trans(not saying you're claiming that) and it's often something that is ignored compared to other features on the body. I've seen this go around on art boards, asking if taking digit ratio in account is important, and the general consensus is that it's not something that's really noticed or recognized.
I suppose to an FTM, they might take it with some pride, though.