I'm not sure why you would buy a brand new, warranted tractor of any make at all if it only has 135 hours in 5 years. I do 100+ each year on my Massey GC1720. You could have saved thousands more with a comparable, but used tractor.
When all is said and done, you could send a respectfully worded request to LS corporate and request reimbursement. Worst they can say is NO. As for the warranty down the road if you did need to actually use it for something major, the Magnuson Moss Warranty Act would prohibit them from voiding the entire warranty for using a single non-LS part. The only thing they no longer have to warranty is THAT specific 'unauthorized' part. You change a wheel seal and the engine blows...that wasn't caused by a wheel seal, so the warranty must be honored.
Magnuson Moss Warranty