Fever after baby’s 4 month shots

So I took him in yesterday for his 4 months shots everything was normal till the night like at 11pm. His temperature went up to 101.4. It has been an hour in half and already gave him Tylenol and check his temp and it went down to 101. Should I be alarm. I don’t have anyone to give me device so I’m not sure why to do besidesjust checking on him I want to be checking every hour for his temp but since I do it thru is but area I don’t want to keep sticking that in every hour.