Got second dose since I forgot that I was vaccinated for yellow fever traveling to guatemala long ago?
Yellow Fever 10 year. Yellow fever needs to be updated every 10 years. If you have lost your certificate or are unsure of the date of your prior dose you can get another at any point (you don't have to wait 10 years) check with your travel medicine specialist. Yellow fever vaccine is recommend for far fewer destinations than many years ago. Of course there are many other medical issues to review re: your travels.
No problem. Yellow fever vaccine is a "live" egg based vaccine sometimes "required" by destination country for int'l travel (public health measure). You have to have had vaccine 10 days before country entry. Vaccine is officially good for 10 years. Although quite safe, there are some risks, particullarly as you get older. If it has been a "long time" (> 2 yrs?), but less than 10 yrs, 2nd dose should be safe.