Cloning to short?

Ok i want to top my plants for clones they are about 5 weeks old now and about 9 inches tall and on the sixth node I cant seem to get more than an inch and a half between nodes is this going to be to short for clones.....could this be because that they are f1 hybrids indica dominant

Just cut a few nodes down then trim the extra nodes above the soil

Thanks for the info but i think im going to move my lights up for few few days and get more stretch hopefully