Most Catalinas seem to have a slight list to one side or another. It is due to the location of the heavy interior stuff (the Galley, batteries, etc). Some people have gone to the extreme of glassing lead weights on the high side to correct for this list. Most people simply stack their gear on the high side, and don't worry about it (as long as it is only a few degrees.)
The primary disadvantages of this list are that the boat might sail a little higher and / or faster on one tack than on the other, and your boot stripe on the low side might get more fouled (due to being either closer to the water or possibly partially submerged) than the other side.
Structurally, the slight list is nothing to worry about.
Steve
Alchemist C-30T #4764 (slight port list)
Alchemist C-320 #909 (slight port list)
Alchemist C-380T #71 (slight starboard list)