Hard starting is not necessarily related to oil pressure so I would think you have another issue. However, if it only did it once, I wouldn't worry until it gets more consistent.
As for the oil pressure going up to 80, do you know what oil they used? Did they use a thicker oil?
However, this normally would not cause it to be intermittent. It sounds like you may have had something plugging the relief valve in the oil pump so it couldn't regulate the pressure. Then it gave way and the pressure came back down. It may be worth while do drain your oil and look for metal flake. If none is found, fill it back up and see if it continues to happen.
Unfortunately, the only way to test these types of issues is to know when it is going to do it.
Here is a guide on hard starting so you can start thinking about the things we need to do if the starting issue continues:
Wednesday, October 9th, 2019 AT 7:40 PM