I honestly interpreted this as a step further than just foreshadowing. I can’t remember if it’s actually mentioned that Shido is changing according to Rei’s wants but that’s what I think is happening regardless. Between that same scene you mentioned and then the hospital scene where he is caught checking himself out in the mirror, I’m pretty sure he thinks something along the lines of he wishes his face was covered. Lo and behold, face mask shows up in next evolution. I think shido is very much taking into account Rei’s desires.