Hi Sukanya,
SD0080 check is about data collection design. Its purpose it to ensure that dates for study completion are collected. If number of warnings generated by check is high enough, then it is a signal about missing dates for subject study completion.
You are correct there is nothing wrong in your case. Few data collection issues are expected in each study. Per FDA requirements you need to provide explanation in Reviewers Guide (SDRG) document. Something like: "Few subjects have AEs reported after their study completion dates. For example, subject xxxx has study completion date as 2015-05-30 (DSSTDTC). This information was recorded on 2015-05-31 (DSDTC). Subject had reported AE started on the same day 2015-05-31 (AESTDTC)"