One bed bug from somewhere else?

yes it is. That is how bed bugs are spread. You need to wash your clothes in HOT water! and if you had a bag that you took over there, wash that too. If you have already slept in your bed, take all of your sheets off and wash them too. Then vac all your mattress, bed frames. You can tell if they are bed bugs because they bite two or three times in a line. Known as the 'breakfast lunch and dinner' bites. So that is a sign right there that you have them, if you went to be and woke up with bites like taht. Good luck!