First part: thats fair, your wording above seemed to imply otherwise. Even if that was true, it wouldnt have painted you as anti-trans, if thats what you're worried about here. You can respect someone's identity while also growing apart from them as they change, happens along many axes. Axis'? I think axes.

Regardless, I dont think retroactively editing your thoughts at the time does them any meaningful favours or respect? You had no idea they were trans, why apply what you know now to a past you that didn't?

Its how you feel about them now or since that matters, in this regard.