Hi there.
The technical answer to your question is yes, but it's very unlikely.
The fact is that you can really never know if he's ever been with anyone else - orally or otherwise.
Here's what Avert.org says on this topic:
Sexually Transmitted Diseases (STDs) including common STD symptoms
What are sexually transmitted diseases (STDs)?
Sexually transmitted diseases (STDs) are diseases that are mainly passed from one person to another (that is transmitted) during sex. There are at least 25 different sexually transmitted diseases with a range of different symptoms. These diseases may be spread through vaginal, anal and oral sex.
Most sexually transmitted diseases will only affect you if you have sexual contact with someone who has an STD. However there are some infections, for example scabies, which are referred to as STDs because they are most commonly transmitted sexually, but which can also be passed on in other ways.
What are sexually transmitted infections (STIs)?
Sexually Transmitted Infection (STI) is another name for Sexually Transmitted Disease (STD). The name STI is sometimes preferred because there are a few STDs, such as chlamydia, that can infect a person without causing any actual disease (i.e. unpleasant symptoms). Someone without symptoms may not think of themselves as having a disease, but they may still have an infection that needs treating.
Take your time and wait until you're both ready and practice good hygiene. Wash up before oral sex to reduce the risk of transferring bacteria. Use a condom for him to be extra safe.
Look, we're not here to preach fear and wrath. There are dangers that we face every day. Driving is dangerous. Walking down the street is dangerous.
The important thing with STDs is to do your research, be informed, and understand the risks so that you can make an informed decision.