I got on of the early Groove Skates (I think) in the US back in April or May of 2018. Love the board and it is so fun to ride. I'm on Moses 633/483/101 . I ride strapless only, so I have never jumped with the board (in fact it has never had straps screwed into it.)
Recently over the last 10 sessions or so, I have a slight "creaking" sound under my back foot as I am pumping / working the board. Closest analogy I can make is old wooden floorboards creaking when you step on them. At first I thought one of the base plate screws was loose in the track but I checked and they are all tightened down. I'm a bigger guy (100kg) but I'm not jumping at all. I really don't feel any heel dent or pressure dings when I press hard with my thumbs there. It almost sounds like maybe a stringer is creaking against the foam inside the board as the board flexes slightly?
Anyone else who is a long term Groove Skate rider notice anything similar? Any other hypotheses?