hi gena, well IMHO, i would make sure he can sleep in his crib, not only on the swing, 'cause as he gets older it would complicate things, but if he can sleep in his crib, i don't think its HORRIBLE to let him take the catnap in the swing... i would preferrably not do it, but the catnap is evenually going to disappear in a few months... so i guess there is no harm in that...
but perhaps you can post your routine so we can see what's happening?