If you have the right crush washer, either the plug is not tight enough or there is some dirt, etc. under the washer. If the latter is the case, you don't have to wait until the next oil change. Loosen the plug (don't remove) and clean underneath the washer with a cloth or toothbrush. If it's not the right washer, you can remove the plug and put your thumb over the drain hole and not spill more than a few drops of oil. Push in on the plug as you loosen it. When you have it unscrewed, slide your thumb over the hole as you remove the plug. Just have someone to help you and do the job when the engine is cold. Have a drain pan in place just in case. If you tighten the plug with a combination wrench, it is unlikely that you will over torque it.