No, it isn't weird. A lot of women don't orgasm from vaginal sex. What is it about your husband's orgasm that makes it feel good for you? Is the mental side and knowing that he had an orgasm? Is it the physical side, maybe the extra lubrication? If you think it might be that extra lubrication that you are getting from his semen that is making it feel good, then you could try buying some lubrication at the store.
Don't be afraid to guide your husband during sex or have him explore your body to find out where you are the most sensitive. Keep in mind that some women are not very sensitive, so don't get down if you don't really find any sensitive spots. You know what you like enough to orgasm during masturbation though, so try to see if you can incorporate what you know about your body and what it likes to when you are with your husband. It can, but does not have to be during vaginal sex. Many women orgasm easier during oral sex.