you need to be reading the temperature of the absolute bottom of the enclosure and adjust your thermostat accordingly, not the top of the substrate. the snake WILL burrow down; this is not an if but a when. the absolute bottom should of the enclosure should be around 90° F; the temperature on top of the substrate should be disregarded when adjusting the thermostat.
EDIT re-reading your post: so your warm spot is 95°, not 88° F, which IMO is too high when you can adjust it with your thermostat. adjust the thermostat so the bottom of the enclosure reads 90° F and you're good to go.