main rear seal on a ranger

i changed the main rear seal on my tranny and ive got a whining noise now whenever i let off the clutch to go in first or reverse. we had to take the driveshaft off to get to the seal so im thinkin its something to do w/ that. pops told me it may be the seal gettin broke in since its new but thats sound ya know. im thinkn we f'd somethin up but if anybody has any suggestions let me know please...sorry bout the book 2..pce