Low Post-Boil Volume / Higher OG Question

My post boil volume yesterday for a 5 gallon batch was around 4.5 gallons, and my OG was 1.080, instead of the 1.072 target as listed on my recipe directions. I sparged with the amount of water the recipe instructions called for, so I think the reason for this is because my boil pot is 15 gallons and I am getting alot of boiloff. Should I, now a day later, consider adding some additional water to my fermenter to bring the volume up to 5 gallons? Or, should I just call it good and let it stand as is? Will this affect to finished flavor, etc.?

what was the volume before the boil? how long was the boil? and personally I'd leave it as is and just enjoy the beer you made..

Probably fine to just leave it. But what style beer is it? Your bitterness might be a bit higher than planned, so if it is lightly bittered you might want to dilute it to get the right balance. If it's something like a big IPA or APA, don't mess with it. The extra bitterness (which is probably minimal to begin with) will probably not be noticed and the extra ABV will onyl help!

I had efficiency problems on an English pale and had to boil off a bunch to get the same OG, around 3.75 gallons instead of 5. I didn't think to adjust the hops and it is certainly more bitter than it was supposed to be. But it's a good thing I like hops, the beer is still very good.

EDIT: Probably best to wait until fermentation is fully done to think about dilution. If you still get close to the recipe's FG, best to leave as is.

The beer was the AHS Pliny Clone. Preboil volume was 6.5 gallons, and the boil time was 90 minutes. I am surprised that the recipe directions didn't seem to account for the longer boil, unless 1.5 gallons boiloff is typical. Maybe my larger 15 gallon pot makes a difference.

in my 10 gallon pot a 90 minute boil will boil off 1.5+ gallons.. 6.5 gallon is what I use for a 60 minute boil. that's so I end up with 5.5 gallons (to account for the trub loss after fermentation)

Curious if you have any updated (consistent) measures on boil-off volumes? I am searching/asking because I did my first 15 gallon AG today and I lost 2.5 gallons in an hour! This is a Polar Ware 15G which has a wide surface area. Also it was 40 degrees and 90% humidity.