Yes, as the Tobacco Use Sample Notes page states the longitudinal links you’ve noted are valid links. Also note, although official documentation does not state as such, it seems that the July 2014 and May 2015 TUS samples are also able to be linked longitudinally. See this User Forum question and answer by a user who stumbled across this possibility. As it sounds like you have done, after linking these individuals with CPSIDP and verifying the links are legitimate by checking demographic information, it is safe to assume these are the same respondents.