What Causes Vaginal Bleeding After Having Sexual Intercourse?

my first lovemaking i was 33 then but it was not often since after 1 mos my husband have to work back abroad, we have contact again november 2008 and we just together for 15 days only and our love make was not everyday, last december 31 we met again and have our lovemaking but after 1 mos i experienced to have blood spot after lovemaking do i need to see a doctor? do i have to get worry about this? please help..