Well, obviously I'm just a little biased, but I don't see anything wrong with getting it checked out now (especially if insurance will cover it), even if it's just for peace of mind. Being only 20 years old now, I'm living proof that cancer doesn't necessarily wait on age.
That said, if you're getting a physical on a regular basis and you're not having any odd pains or health issues, I doubt that it's really an issue for you yet. Don't guys usually start getting that exam at 40? If you're really worried about it, you can always start earlier (especially if there's a history of cancer in your family)...but if you're not, then I wouldn't be too worried about it, either.
That said, if you're getting a physical on a regular basis and you're not having any odd pains or health issues, I doubt that it's really an issue for you yet. Don't guys usually start getting that exam at 40? If you're really worried about it, you can always start earlier (especially if there's a history of cancer in your family)...but if you're not, then I wouldn't be too worried about it, either.