Slippage and thinning locs

Been loc’d about 16 months. The first year I didn’t experience any slippage, lost locs. Lately Ive noticed my locs seem thinner around the edges and I’ve lost two locs this last week from what looks like slippage! I’m freaking out. I don’t do anything different besides go to the gym more. I did start seeing a new stylist around my year mark. She pointed out a loc that was thinning and since then I notice a difference in my locs integrity. Could it be the method she uses to retie? The sweat from the gym? I make sure to completely dry before manipulating my hair after the gym.
I plan to try and go to my original stylist next month (she’s 3 1/2 hrs away)