you can try putting the water bowl closer to the heat source as well. That will warm the water and create more humidity. You can also cover half of the opening on top with a hand towel or something that will help insulate and keep the moisture in while still leaving some ventilation openings exposed for air flow.
I wouldn't worry too much as it will likely fluctuate throughout the day and night. Unless you see shed issues, you should probably be fine.
I do not do anything extra to bump up the humidity for my bp's, however they are in rack systems which definitely keep humidity in when I spill water or if the animals splash it around (yes I am convinced some of my animals intentionally make water messes in their enclosure. they are special)
any who, you should be good so don't sweat it