Unless you've got a temperature controlled PSU fan, and it's very very cold where you are, then no, it's not a good thing. Will it start if you nudge it with something (use chopsticks or a wooden spoon)? If not, your fan is stuffed. Buy a new PSU. It's probably not worth replacing the fan. Or keep using it, and get ready for that lovely dusty electric train set smell, followed by a fire