Check the properties of the flash drive. There are two settings. One, allows you to remove the drive anytime. The other, performance, you have to ask to remove the drive. Removing the drive when in performance mode without checking to see if it is safe to remove the drive can damage the USB ports.
I do not recommend sticking your flash drive into public computers. People change things on these, accidentally and sometime maliciously. A setting on a public computer can change the setting on your computer without you ever knowing it happened.