Short Answer

No, you do not have to bathe again since only the semen which comes out during ejaculation requires bathing (ghusl).

What the Scholars Said

Imam Abu Yusuf said: “…according to Imam Abu Yusuf, its exiting from the private parts with gratification is also necessary (to require ghusl).” (Al-Hidaya, 1:31)

Imam Abu Hanifah and Imam Muhammad said that if you held the tip of your penis during ejaculation so it did not come out, but dripped out later, you must bathe (ghusl); however, if semen exited after urinating or sleeping, then it will not be necessary to repeat the bath, for sleeping and urinating clears the passageway. (Al-Lubab fi Sharh Al-Kitab 1:40)

Advice

If this rarely happens then it is better to bathe again because many scholars have said you must, so it is better to avoid the different opinions and be on the safe side for something that is not very difficult.

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Shaykh Mustafa Umar