All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
If you are affected with Waswasah (obsessive doubts), then you should ignore it and not pay any attention to it.
Moreover, this wetness might merely have been sweat or anything else. If it is probable that it could be either pure or impure, then in principle it is pure.
Hence, you did well by ignoring this matter, and you are not required to do anything in this case.
Allah knows best.