A question about slugs.

Okay, this is going to sound slightly ridiculous but I have a question about slugs.
I have a very large-for the city- back garden, and mostly it is filled with a raggedy lawn, mature bushes and hedges, a huge black berry bush, and very few actual flowers. Until we have more money at our disposal that is the way it shall remain too.
Because I don't have a lot of flowers, except for some troughs filled with pretty hardy Geraniums, I don't really get into a flap about snails and slugs. I don't like killing them, I just don't. I usually move all the visible snails off the lawn before I mow it and there was a slug that looked like a small walrus sitting by the kitchen drainpipe yesterday that I moved onto the lawn with a stick.
(I know this sounds more daft as I go on, bear with me.)
However, the last few nights I've noticed something odd. I put the cats out into the garage every night and I feed them there. Apart from the Marklar, the Bigger of the cats and Puddy have their bowls on the floor (concrete) But all this week I have been finding two pretty hardy looking slugbuts in their bowls before I feed them. Normally I toss these chaps out, rinse the bowls then feed the cats, but lo, they are back again the next night.
So, pondering this, last night instead of tossing them out I plonked the very smallest piece of cat food (cod in jelly) down for them (the slugs) and went to bed (upstairs).
This morning it is gone and from all the silver trails it seems they went for it like crack starved junkies. Now maybe they're just coming in because the weather is getting colder, but it does seem they make their little sluggy way in at the same time every evening, and they do seem to make their slugbutty way to the same spot. So what do we think?
Is this odd? Do slugs like cat food?
Or am I spending a bit too much time thinking about slugs?