Yes, but not maliciously so.Ok help me out here. If I never identify as cis when introducing myself (with the exception being in a cis/trans rights discussion), because how I got to be my gender is none of your business and I don't care how you got to be your gender, am I being transphobic?
The problem is the same inherent in the phrase "I don't see colour." You're not being inclusive or welcoming of PoC when you say that. You're just telling them not to rock the boat. Discouraging them from talking about social issues. When you tell trans people that you don't care about their gender, you may think you're being more welcoming than your garden variety transphobe, you're really not. You're telling them to shush. Saying that your (cis) gender is none of anyone's business is coming from a place of privilege. It's easy to say that you don't care about gender identity when your identity hasn't been demonized for centuries.
I don't think you're a transphobe, but it's easy for well-meaning people to exhibit behavior that is transphobic in nature. It's worth reflecting on.