This morning while using Litche I noticed after 15min of flying that when I returned home the screen reading for altitude was off 42'. It showed 52' high on the screen when it was really only 10' high. This evening when it was cooler I was at a different location running another Litchi mission. Sure enough when I returned home is was 53' off this time, showing 61' high on the screen when it was only 8' high. I thought it was a Litchi issue because I hadn't notice this before with the Go app. Then at the same location just minutes later, I flew with the Go app for about 15 minutes, a 5mi trip. I came back and the altitude was fairly accurate, only about 6' off, showing 13' on the screen when it was really only 7' high from takeoff point. I felt this was an acceptable tolerance. With that test I thought for sure the problem was with Litchi. However I flew a third time, again using Go, and when I returned it was 55' off, showing 63' on the screen when it was actually only 8' high from take off point, so it's not just Litchi, which makes more sense to me since altitude comes from the barometer. Have others seen this anomaly? Is this a known problem I just haven't noticed before? I don't recall anyone else reporting such an issue, correct?