Rear Main Seal leak

Fired up my 440 on Monday. Everything sounded good, good oil pressure, no over heating issues. Ran it for 20 minutes at 2000 rpm's to break in the cam. Then alas I look under the car and see a puddle of oil. Put it on the lift and wouldn't you know it, the rear main seal was leaking. When I built this engine I installed the "red" high performance rear main seal from Fel-Pro. Everything was done correctly except I didn't stagger the rear main seal. The engine was built in 2014 and fired it up this past Monday. Is it possible after sitting for nearly 7 years on an engine stand that the rear seal could have dried out? I ordered a new red seal along with a stock type rubber one to get the side seals as the red one doesn't come with side seals. I dropped the drag link and the oil pan, pulled out the main seal bridge and the rear main cap. Cleaned everything thoroughly and re- installed it with the stock type seal except this time I staggered it. Hopefully it'll seal up this time. Has anyone else had this issue?