Mono line for tuna fishing

[togzilla]

Love bouncing questions on this site for unbiased opinions.
Changing some of my line on my tuna reels for one last trip. I have not been in 3 years due to poor fishing and being blown out. Question I have is one of my reels I have 65lb power pro with a 100 yard topping of 60lb blue diamond momoi. I put the line on new 3 years ago and only used it once. The reel has been stored in my garage with no exposure to sunlight. The line looks brand new but should I change it? If I keep it I would run it behind the boat on the way out to remove the coiled memory of the line from sitting on the reel for 3 years. Being it's only 3 years old, used once and looks brand new should I change it?
I know it's not much money to change it but seems like such a waste. If I ask any tackle dealer they will all say to change it to sell me more line.
What's your opinion?