Doesn't change the advise of taking regular snapshots/screenshots of MM balance and date. Unfortunately, I doubt DL is going to do anything if all you have are suspicions from past flights with no hard evidence. gcmap.com and milecalc.com distances usually match DL credits for MM. I've found a few exceptions like DEN where DL is clearly still using Stapleton location to measure distances. But if you just want to check distances within a few miles they are perfectly fine.