Water down the inside? (Yup!)
I have the same situation with my '88 Olson 34. When we got this boat in '94, it was our first boat with a keel-stepped spar, also. What with all the halyard in's and out's, and the slot at the base of each spreader on a double spreader rig, there are a LOT of little places for water to get inside the mast. Just make sure that the drain hole at the foot of the mast stays clear. I run a small wire in and out of mine every so often. In our case, the spar is stepped on a glassed-in beam that keeps it above the bilge. I do not know about your model, but some boats have the base of the mast way down in the bottom of the bilge where they stay wet and can corrode. As long as you keep the bilge sponged out after a rain, it's just part of the routine of "big boat" ownership (!). I dry out our bilge once or twice a week during a rainy winter. What with a PSS shaft seal for the engine, this is the only water that ever gets in our bilge.
Speaking of bilges, I just finished rough-sanding our whole bilge area and gel coating it out in white. The sole pieces needed new varnish anyway, and now they are back in. While I was at it I opened up some of the limber holes a bit so that water could more easily move from one section to the next. It was also time for renewing one the bilge hoses and checking/replacing strumb boxes.
Welcome to the world of "second home" ownership!!
Fair Winds,
Loren