I was cleaning my bike the other day and noticed that the boot on my lefty had slipped and moved up a little bit (the zip tie was still on the boot but the boot moved up away from the hub). A little bit of grease or oil was seeping out of the bottom of the boot. I have had the bike for 2 years. Do I need to worry about the boot sliding up like that? Also, how often should I get the fork serviced? It is a lefty Jake.