i had the fork seals replaced ~900 miles ago. the left one is leaking again. the same one that was leaking before. i don't abuse my motorcycle, i ride 90% on the interstate, and a little around town.
this will be the third time i've replaced the seals since i have bought the bike. 1 1/2 years ago.

what could cause this? it is very aggravating, although i'm looking forward to learning how to do suspension work.

 

chips in the fork from rocks, excessive dust, dry weather, bugs and other debris...

 

yea, check your forks for chips or other 'rough' spots that can cut the seals upon compression. i usually run it through with some steel wool.

 

There are a couple of other things that can cause premature failure, overfilling the forks with oil, bent fork tube (not always obvious in the triple clamp), the wrong oil seal, Re-inserting the springs in the wrong direction (the springs coils are closer at the bottom), if the fork tube hidden by the seal was scored when the old seal was removed (includes removing the snap clamp) or the fork slider was scored trying to do same. Did you do it yourself? or have the shop do it for you? if the later, are you taking it back to the same shop? (which would make to me a bit wary).
Oh nearly forgot, are you just replacing the one fork seal, cos if so, different grade oils in one to the other can do it to (more pressure on one)

 

no i got them replaced at the same time at our local honda shop.
this time though, i am going to do it myself (i finally have a front stand).

it has really aggravated the **** out of me, and if it happens again, i'll know it was my fault.
and if it doesn't happen for a long time, i'll know it was the shop. assuming i get it done correctly.

What happens if the fork tube is scored? what can i do about that?

 

you can try to sand out the sharp areas, etc. to prevent it from cutting up the seals again.

also, make sure you use OEM seals...the aftermarket reusable ones tend to leak.