Agreed, if the reins are too long, then you should really sell them and buy a shorter pair or trade them in (if yours are new) for a shorter pair.
You are riding western, right? Are these split reins? I don't know about anyone else, but I like for the tails of my reins to hang somewhere around the horse's knees. That ensures I've got plenty to ride with my reins slack the way I like and the tails are long enough to stay out of my way.
The way I see it, if the horse is almost stepping on the ends, then they're the right length LOL.
Most split reins are either 7 or 8 feet long...but I'm actually searching for a pair of 10 footers right now because I've got a monsterous horse I'm riding and 8 footers are waay too short LOL.