If they're not leaking I wouldn't bother tbh.
DON'T UNDER ANY CIRCUMSTANCES USE WD40 on the seals to aid fitment, this dries them out and can cause ripped seals when trying to force them in the rail/inlet.
Just use some std hmp grease on the seals, they will literally fall in, or out as was the case yesterday for me, then had to clean it all up again, they go in so easy just the weight of the injector can make it slide out again from the rail, so I put them all in the inlet first, put rail on top and push down gently whilst wiggling from side to side slightly, don't worry too much if a spec of grease goes in the filter basket on the top of the injector, the petrol disolves it and causes no harm.
tabetha