It could be from a client that doesn't use sensitive content yet. Our expirence is that people report a lot more when the author doesn't use it.
Discussion
Ok that's going to be a problem if the person and client doesn't use a client that supports that. The question is this reports going to have a repercussion in the future? .
If they are not malicious reports hopefully they muted you and the client is upgraded when the author of the client notices the ongoing reports. But give your #nsfw tag time as some people may be obsessed with reporting your account, having been embarrassed in the way described above.
Every client and every relay can interpret these reports in any way the see fit. So, no one knows. But I think generally people have been pretty good in evaluating such reports.