Drip, Drip, Drip....Follow the Drip!

-1994 Buick Lesabre
-This is the second time that I have done an oil change on my car and I have noticed that I am leaving small puddles of oil on my garage floor, gradual of a leak as they may be. Both times, a new gasket was put on, gasket sealant, and still it leaks. The one thing that I have noticed both times is when I am putting the bolts back is that some are different lengths, even as slight as they may be. Could this be the problem? Some aren't going all the way in and giving a proper seal? Maybe I should go to an auto parts dealer or the car dealer and get a new set.....although my resident expert at work tells me that I need to take them with me to make sure the threads match...
Any input is welcome :banghead:

when I am putting the bolts back is that some are different lengths, even as slight as they may be. Could this be the problem? Some aren't going all the way in and giving a proper seal? Maybe I should go to an auto parts dealer or the car dealer and get a new set. Are you talking about the oil pan drain plug shown below? If so, where are all the other "bolts" going?

http://www.partsamerica.com/product_images/img/dor/090-079.jpg