A Corn's ideal maximum temperature is below human core body temperature. They should always feel cool or cold to you when you touch them, unless you pick them straight up from the warm side. Mine spend most of their time on the cool side, so that's normal. You just need to check that your warm side isn't getting too hot - 85 degrees would be ideal. If it's more than that, then your Corn may be avoiding it as overheating is more dangerous to them than being too cool.
Snows can develop a yellowish wash as they grow, especially on the third of the body nearest the head. I think it's just a sign that he's growing up!
This all sounds normal to me and nothing to be concerned about.