Water in the hull over the winter

[Sean]

Alright, lat weekend I put her down for the winter. :-[ Cleaned her up real pertry, winterized the engine, removed the battery and tucked her in with what I thought was a water proof cover. Under the impression the cover was water proof, I left her titled a little forward to enable me to leave the engine completely vertical ( park on a slope). I also dumped a gallon of anti freeze in the bilge area just in case any water gets trapped.
Well, with the rain today I found out that were was water puddled on the tarp it was slowly seeping in. I am going to re-cover with a frame running down the center of the hull to prevent the puddling and I hope prevent water from getting in to the boat.
Should I be worried if a little water builds up in the hull?? I am planning on dumping anti freeze in her once a month so I think I should be all set? Correct me if I am wrong but I would rather make sure my engine has no water build up then my hull? The antifreeze should prevent it any way??
Sorry, board @ work
Thanks!