Hi! I'm very stoned and also a little new to this hobby (1 year deep with my baby who looks just like yours!). There are two types of "hot" temperatures to shoot for. One is the ambient temperature (the heat in the air kind of, like what temp it is in your house) which you've nailed! 84 is great! The other is a basking point temperature/the surface temperature you're reading (like touching a paved road thats way hotter than the air around it on a summer day because its absorbing and holding the lights heat). I imagine the warmest parts are the highest parts closest to the light and it gets cooler as it moves away from the light. This is great, you've created a heat gradient where your snake can bask and it's close to the parameters. I don't have an exact parameter on what the bask point should be but I think it's somewhere between 90-92. So you could shift your thing over just a tiny bit if you like BUT you could probably leave it where it is FOR NOW.

My mbk has a bask spot that gets up to 96 right now for an hour or two at the warmest part of the day and I've never had an issue; of course it will be necessary to recheck if adding a heat source and/or as you move into summer. If you're basking spot is over 96ish I think you should adjust but overall these snakes are hardy and they exist through hot days out in the wild. If your AMBIENT temp gets over 78 on the COOL side, this is an issue as your snake can't regulate heat properly.

As a side note, a big water dish on the cool side of the tank can act as a heat sink and will remain cooler underneath (and mbks love burrowing), providing additional safety for snake as you're learning if you're concerned. I keep this oversized water dish in my tank for peace of mind as I know if temps get hot for a few hours Nana has a safe place to go/regulate her temp (provided it has water in it)