Help. Please Read. Pre Cum

So me and my ex had sex on this past Tuesday.  7/25. We had unprotected sex but made sure he peed before and I tell him not to do any self pleasuring days before we even have sex so there is no chance of pre ejaculation present. So the second round, he claimed he was about to cum so i got off but he didnt cum anyways. So we stopped after that. Maybe 20 minutes after we had like a quicki and no ejaculation happened. He didnt cum at all during us having sex.  But I was thinking since he felt he was about to cum, is there a chance it like came up and could be present in his pre cum in the time we had sex again?