Replacing Dental Sealants As an Adult?

I had sealants put on my molars in 95 as a requirement before orthodontic treatment. I completed 5 years of ortho. Several dentists, that I have visited over the years, ask how old they are & were astonished that they are still intact. I was told the average is about 5 years for them. Recently I noticed (at least on my lowers) that the sealants are either no longer on or only a portion of them remains. I was thinking about asking my dentist for new ones. Is this advisable for adults (I'm 27)?