That, or they've recently moved from somewhere much colder and still haven't acclimated to the new temperature range. I was this guy for a solid year after moving back home when I'd spent two years living much further north and getting used to a far colder climate while I was at college. 15 years later, my feet start getting cold if I don't wear heavier socks and boots when it dips below 20°C, but I also don't feel like I'm sweating enough to flood my apartment when it starts pushing 40°C in the summer any more.