His penis throbbed

Okay so me and my man was having sex and while we were having sex his dick throbbed in me. ( like it jumped) the only time i feel his dick throb like that is if he is cumming. But strange thing is that he just kept going like it was normal. I told him about it and hes not denying cuming in me. He said he doesnt know but he doesnt think he did. I know my mans body and what his penis feels like when hes cuming. So my question to you all is.. Have you ever felt your mans penis throb in you and he not cum?

Lately he had been cumin fairly quickly in me and i told him I wanted him to last longer. U think ... He may of made a uh oh! Lol