A temp gun is a great thing to have, but you really should run to Walmart and pick up an accurite weather station so you can put the probe on the glass over the UTH. This way you can monitor the temp constantly for swings, instead of just once or twice a day when you decide to move the bedding and shoot it with a temp gun.. You see how that could cause inconsistencies? Being able to just see the temp on a screen all the time, whenever you look at it, is best.
The OP is using a herpstat, I really don't see how he is going to have temp swings with a proportional thermostat.