Stiff Hinge - WD 40 Fixed It

2015 A1502 MBP 13" Retina

Sold one the other day and all was fine, they brought it back to me and said the lid was very stiff to open. I removed the display and checked the hinges and all was well, loosened them and tightened them numerous times to no avail, the display still was very stiff and was lifting the entire unit off the table trying to open it. I got a straight edge tool and everything was fine, no bends in the display or casing. The display was closing but then popping up 3-4 mm shortly after causing the unti to come out of sleep. I tried aligning it 4-5 times to no avail. The antenna side hinge was more stiff than the LCD cable side. So I taped off the screen and squirted a tiny bit of WD 40 into the hinge and assembled the unit again, then all was fine!. Question being, is it OK to use WD 40 on the hinge as I was naturally afraid of any chemicals getting under the bezel gasket and affecting the display. We really tried everything and WD 40 was the only thing that came to mind that might do the trick, and it did. @danj for an opinion please.