Choke flap stuck in engine

That's what i thought at first because i did put new copper washers in when i put my exhaust back on when buttoning everything back together. However, i took a stethoscope and probed around and the sound is definitely coming from the valve train. Thing is, its quiet/barely noticeable upon startup but gets louder as it warms up. Hence excessive valve clearance? Correct me if I'm wrong, but is it that metal expands as it warms up so the clearance would be excessive resulting in it being louder warmed up opposed to just being started?

Seems to me that when the metal expands, the space between the parts gets smaller.

I guess i won't fully know until i get in there (again) and find out with a feeler gauge