Extra Coax?

Just curious... Seems to me I read somewhere that extra coax between 
antenna and radio should not be managed in a coil. Any truth to this? If 
so, what's the issue?

I've got an attic antenna about 20 feet or so from an ICOM R8500 connected 
with 50 feet of RG6-U. This leaves about 30 I keep coiled and wire tied on 
the floor.

Thanx,
Bob